933-2321 ACM I-sheet Proof NEW.pub

933-2321 ACM I-sheet Proof NEW.pub
Turntable Accessory
Advanced Control Module
The Cornerstone® Turntable Advanced Control Module (ACM) can be added to new
turntables using the new ‘two digit’ control boxes. Compatible turntables are shown in
the table. The ACM is not compatible with any prior turntables using the older control
The ACM circuit card is intended to be installed
under the benchwork or inside a custom control
panel and connects to the turntable control circuit at an existing control box, or may be directly
connected to the turntable pit in place of the
standard control box.
A custom control panel using the ACM may be
used in addition to or as a replacement for the
standard control box depending on the functions
Compatible Turntables
933-2618 N Scale 130 Foot
933-2860 HO Scale 90 Foot
933-2851 HO Scale 110 Foot
933-2859 HO Scale 130 Foot
The ACM provides the following functions. Each function is independent of the others
and any or all may be used as required. Refer the relevant sections of the instruction
sheet for details on making connections to the ACM connector headers. All wiring connections use industry standard .1 inch spaced pin headers with the exception of the
DCC track signal which connects to a terminal block.
DCC Control
When enabled and connected to the DCC track power, the ACM can function as a stationary decoder, and translate accessory on/off (ie turnout thrown or closed) commands into turntable track selections. A simple to use ’learn’ mode is used to
enter decoder addresses and no DCC programming or CV settings are required. There are no restrictions on addresses
and any decoder address (1-2044) can be used for any track. After setup, the turntable bridge head or tail can be sent to a
track by setting the associated decoder address thrown or closed . An accessory address can also be used to initiate a turn
(ie reversal) of the bridge from any location.
Serial I/O
An optically isolated logic level serial port can be connected to a remote device such as an Arduino, Raspberry Pi, or similar microcontroller, or to a PC or laptop with a suitable adapter. Simple human readable ASCII commands can be used to
control any turntable function, including programming.
Switch Input
Several options are available to allow turntable control from pushbuttons, rotary selector switches, rotary encoder or numeric keypads. By using these functions, custom control panels can be used in place of or in addition to the standard control box. It is also possible to convert an existing turntable control panel used with older control systems for use with a new
Walthers turntable.
Track LED Indicators
Indicator LEDs can also be connected to the switch contact inputs to provide visual indication of the bridge alignment in lieu
of the track number display. The LEDs can be used with all control modes except Keypad, and are also active if none of the
switch contact control modes are used.
Track Number Display
A two digit, seven segment digital display can be connected to display the selected track number, The display will mimic the
display on the standard control box as well as indicate selections being made in any of the ACM control panel modes.
Track Power Relay Control
Logic level outputs are available to drive relays for track power control. Standard relay module cards may be used directly,
or any standard control relay can be used with a suitable driver.
© 2016 Wm. K. Walthers, Inc. Milwaukee, WI 53218
Check the package for the components
shown. The ACM may be mounted
either under your benchwork near the
turntable pit, inside a custom control
panel, or any other convenient location.
If you are using one of the control
panel modes, locating close to the input switches and LEDs is preferable.
The three jumpers connect to the Option Select header block as shown below. One is used to select the control
input mode, one for setting the polarity
for the relay logic outputs, and the third
for the DCC mode. Attach them temporarily now so they are not misplaced.
Connect the ACM to the turntable conTT Control Power
12-18 VAC
16-24 VDC
250 ma
ACM Package Contents
• Mounting spacers and screws (4)
• Turntable control cable
• Option jumpers (3)
• Instruction sheet
• ACM pcb assembly
trol circuit as shown using the supplied
cable. You may connect a maximum of
four devices to the turntable pit and
have up to three standard control
boxes in addition to the ACM. The
ACM is powered from the turntable pit,
and no other power supply is required.
You will need a separate power supply
compatible with the relays you use for
All control panel wiring to the ACM connectors use standard pin and socket
headers. You may wish to use flat ribbon cable connectors for the relay, display, switch and relay headers. Individual wires with preinstalled socket connectors compatible with the ACM headers are readily available from many
electronic hobby dealers as well as
numerous on-line sources.
• Maximum 4 Turntable Control Devices
• With ACM installed, use of Turntable Control box is optional
Bridge Track Power
(AC / DC / DCC)
Control Box
(back view)
To Home
track power switching if you use that
feature. Do not make any connections
to the other ACM terminals except as
required by the functions you are using
and as detailed in the following sections. Any terminals not used should
be left open.
Control Box 2, 3 & 4
(back view)
Advanced Control
Turntable Pit
(bottom view)
When connected to the turntable control circuit, the ACM DCC and Serial
Rx/Tx inputs and Track Power Relay
and Digital Display outputs are functional regardless of the control mode in
use. The Option Jumpers determine
how the Function Control and Track
Switch inputs as well as the corresponding LED outputs are interpreted
and displayed. Refer to the sections
below for specifics on making connections to each of these headers.
The ACM uses standard .1 x .1 inch pin
headers for connections to external
switches and LEDs. While it is possible to solder wires directly to these
pins, you will find it more practical to
use matching socket headers designed
for this purpose. Molex, Amp, FCI and
a host of other vendors offer compatible products which are readily available
from distributers such as Digi-Key,
Mouser, and Jameco. Online sources
such as Amazon also have many suppliers of these products. Use of multi-
DCC Signal Input
Turntable Control
Activity LED
Switches &
color flat ribbon cable will make keeping track of the many wires much easier as the switch and relay header pin-
outs result in the connections running
in number sequence across the width
of the cable.
Multi-conductor cable and connectors
A handy source of premade connector
wires are jumpers with socket plugs
intended for bread-boarding electrical
circuits. These can be obtained in various lengths and connector configurations. The female to female type will
facilitate making connections from the
relay output connector to standard multi
-channel relay cards allowing unused
channels to be readily skipped. Female to male jumpers can be used to
connect to your switches and LEDs by
soldering the male pin to the panel device (or just removing it to attach the
Breadboard Jumpers
wire) then plugging the other end into
the ACM header. These jumpers are
available from your local electronic
hobby dealer and many on-line
Another source for wiring are RC servo
extension cables. These can be found
in your local hobby shop’s RC department. Extension cables are available
in various lengths up to 1 meter. These
cables are three wire only and feature a
three pin socket on one end which will
mate with the ACM pin headers. The
Servo Extension Cables
receptacle on the other end can be removed when connecting to your panel
components or you can plug them end
to end if you need extra long connections to your panel. Breadboard jumpers will also fit these connectors.
The multi-conductor cables can be
readily separated into individual wires
when needed, and the unwanted connectors on the ends of premade cables
can be removed and the wires connected directly to the panel LEDs and
Connect the switches and LEDs to the
track and function switch inputs as
shown in the diagram. Refer the sections for each switch input option for
details on which switch terminals are
active for each option. Unused inputs
should be left open, and in most cases
are inactivated by the ACM unless
used for the option selected.
nect the track LED anode to the +LED1
terminal and the cathode to the switch
input. Note that resistors are not required for the LEDs, as the ACM uses
a constant current driver to regulate the
LED current. If necessary, refer to the
LED adjust section to set the LEDs either brighter or dimmer than the default
Connect the input switch terminals between the COM terminal on the connector header and the input pin. Con-
You may use switches only, LEDs only,
or both as the need requires.
The Head and Tail LEDs use +LED2.
Note that the Track, CW, and CCW
function inputs do not support LEDs.
The terminals on the track switch inputs and relay outputs are numbered 124. Since the turntable controller supports up to 99 service tracks which can
be assigned any number from 1-99 and
the ACM has just 24 input and output
terminals, the following rules determine
how the turntable track numbers are
assigned the ACM terminal numbers.
As a result, the terminals may or may
not correspond the turntable service
track numbers depending on both the
number of tracks and the numbers assigned to them.
minals as numbered 1 to 1, 2 to 2, etc.
Unused numbers are inactive.
At power up, the ACM obtains a list of
the current tracks from the turntable
controller and assigns each to a switch
input and relay output as follows:
As an example of how the mapping
works, assume the turntable is set up
with 4 tracks numbered 1, 2, 5 and 24.
This configuration satisfies rule 1, and
terminal 1 is track 1, terminal 2 is track
2, terminal 5 is track 5 and terminal 24
is track 24. Terminals 3 and 4 and terminals 6-23 are inactivated.
1) If there are 24 or less tracks defined
AND no track has a number greater
than 24, the tracks are assigned to ter-
2) If there are more than 24 tracks OR
any track has a number greater than
24, the first 24 tracks, in numerical order, are assigned to terminals 1-24.
The track number to terminal mapping
is refreshed on each power up cycle,
so if you make any additions, deletions,
or changes to the turntable service
track numbers, you will need to power
cycle the ACM to update the input and
output terminal assignments.
If the 4 turntable tracks are numbered
1, 2, 5, and 25, rule 2 is satisfied, and
the assignments are terminal 1 is track
1, terminal 2 is track 2, terminal 3 is
track 5, and terminal 4 is track 25. Terminals 5-24 are inactive.
If the turntable has more than 24 tracks
defined, only the first 24 are accessible
via the pushbutton, switch and encoder
input modes. The control box and keypad modes can access all turntable
tracks regardless of number or numbering. The track power relay outputs
are assigned to the first 24 tracks only.
The serial input/output port always has
access to all turntable tracks and can
be used to add input and output functions required for turntable configurations of more than 24 tracks.
A common anode two digit display may
be connected to the ACM and will display the current or selected track in the
same manner as the standard control
box. The display will react to selections made on any control box in the
turntable control circuit and is active in
all modes.
Connect the left-hand digit anode connection to terminal 10A and the righthand digit to 1A. The individual display
segments connect to terminals a-g and
the decimal point to dp. Separate
LEDs can be connected to the dp pins
When connected to the DCC track circuit, the ACM will detect accessory decoder packets in the DCC signal, and if
the decoder address matches an address saved, send a command to the
turntable to rotate the bridge to the selected track. The ACM uses the accessory thrown or closed (on/off, diverging/
straight, etc) command to specify head
or tail alignment at the specified location. An address can also be stored for
the turntable turn function which will
cause the bridge to reverse the alignment at the current location.
Note that the ACM itself is not a DCC
decoder, does not have a DCC address, and does not have any CV registers to program.
When placed in the ‘Learn’ mode, the
ACM will store any accessory address
received and associate it with the current track location. Any valid decoder
address from 1 to 2044 can be stored
for any track location or the turn function. Note that all decoder addresses
may not be available due to limits of
various DCC systems.
Manufacturers of DCC systems are not
consistent with the way they refer to
accessory decoder addresses or the
on/off states of the decoder outputs.
For the purpose of these instructions,
we will refer to the accessory address
by number, and the two decoder states
as ‘Thrown’ and ‘Closed’ which is commonly used for decoders which are
presumed to be controlling turnouts.
Your system may use diverging/
straight, on/off, or other terms to refer
to the two decoder states.
As shipped, the ACM has as defaults
decoder address 1 assigned to track 1,
if you do not wish to use the display
decimal points for the Head and Tail
indicators. The Head and Tail function
switch terminals also provide an LED
output which duplicates the digit decimal points.
Display brightness is adjustable. See
Appendix A for details on how to set
the level.
DCC Quick Check
• Connect DCC track power to the
DCC Input terminal block
DCC Jumper Settings
• Place DCC option jumper on Enable
• Send a command to accessory decoder address 3
• The bridge will reverse ends at the
current location
address 2 to track 2, and address 3 to
the turn function.
To familiarize yourself with how your
DCC system interacts with the turntable, try the Quick Check first. Next,
send commands to address 1, and
note which command causes the head
end of the bridge to move to track 1.
This command corresponds to ‘thrown’
and will be used to save a decoder address for a track. The command which
sends the tail to track 1 corresponds to
‘closed’ and is used to delete the decoder address for the current track.
If you are having trouble with sending
commands to the default addresses, try
the experiment shown below to determine how your system works. Make
certain you know how to send accessory decoder commands before you try
the experiment.
Once you are familiar with commanding the turntable with the default addresses, proceed to the DCC Setup to
complete the learning process for the
service tracks you wish to access via
your DCC system.
The ACM stores the DCC addresses
separately from the turntable controller.
If you add or delete track numbers with
the turntable controller, you will need to
make matching changes to the DCC
addresses on the ACM.
DCC Experiment
• Connect DCC track power and place
the jumper on ‘LEARN’
• Move the bridge to a programmed
• Send a thrown/diverging/on/etc command to an accessory decoder address
• Move the bridge to another track
• Send the opposite command
(closed/straight/off/etc) to a different
• Move the jumper to ‘ENABLE’
• Send an accessory decoder command to each of the addresses. The
turntable will respond to only one of
the addresses used
• The command used for the addressable track is the command to save in
Learn Mode, and move the bridge
head to the track in Enabled mode
• The command used at the other
track is used to delete addresses in
Learn Mode, and move the bridge
tail to the track in Enabled Mode
DCC Setup
DCC Notes
DCC Notes
1) If you have not already done so,
connect the DCC track signal to the
DCC Input terminals
• In Learn mode, a ‘Thrown’ command
stores the address, a ‘Closed’ command deletes it
• When using the Turn function DCC
address, either “Thrown’ or ‘Closed’
will initiate the turn
2) Place the DCC Option jumper in the
‘LEARN’ position
• In Learn mode, accessory decoder
commands are associated with the
Turn function if the current location is
not a programmed track
• Moving the DCC Option jumper to
the ‘DISABLED’ position will stop the
ACM from generating turntable commands for stored addresses
• To delete a stored address, move to
the track, change to Learn mode,
and issue a ‘Closed’ command to
any address
• Sending an accessory command to
the turntable while it is in motion will
cancel the current move and stop the
turntable bridge
• Adding or deleting DCC addresses
can be done at any time and has no
effect on the turntable track numbering or location
• Any turntable motion started with a
DCC command may be cancelled by
pushing any button on any control
• A new address overwrites any existing address for the current track so it
is not necessary to first delete an old
• In Learn Mode, any accessory command received while the bridge is in
motion is ignored.
3) Move the turntable bridge to the
track you wish to program
4) Wait for the bridge to stop at the targeted track
5) Issue an accessory decoder ‘Thrown’
command to the address you wish to
use for the current track
6) The bridge will execute an alignment
jog acknowledging the stored address
7) Repeat steps 3 through 6 for each
track you wish to store
8) To program the Turn function, use
the manual rotation controls to move
the bridge to any unprogrammed
• It is not necessary for accessory decoder addresses used for track access to be sequential or grouped
• In Learn Mode, the ACM will acknowledge receipt of an accessory
command by jogging the turntable
9) With the bridge stopped and the numeric display showing “- -”, issue a
‘Thrown’ command to the address
you wish to use to reverse the bridge
• Any accessory address (1-2044) can
be used for any track or the turn
• DCC accessory addresses may be
added, deleted, or modified with serial I/O commands
10)When done, return the option
jumper to “ENABLE’
• DCC accessory addresses reference
the turntable tracks by number, not
The ACM Track Power Relay outputs
are logic level signals intended to control a relay in the service track power
circuits. The ACM will energize one
relay at a time corresponding to the
current track. The digital output can be
configured as active hi (+5V) or active
low (0V), and the relay will activate
when the turntable bridge starts a
move to a new service track, allowing
any engine decoders at the new track
to fully initialize prior to the arrival of
the bridge. If the bridge is stopped
between programmed locations, all
track power outputs are off.
Review the Track Input and Relay
Numbering section and be certain you
understand how the track relay output
numbers correspond to service track
numbers. The assignments will not
reflect any additions, deletions or
changes made by the turntable controller or serial input until the next power
cycle occurs or a reset command is
received by the serial port.
You will need an external power supply
matching the relays used for power
control. Only one relay is active at any
time, so power requirement is low. A
spare cell phone charger or USB wallwart makes a handy supply when using
5V relays.
The ACM logic outputs cannot supply
sufficient current to power a relay coil
directly and a driver transistor, optocoupler or IC is required to provide the
current necessary for a relay coil as
well as accommodate commonly available control relays with 5V, 12V or 24V
See the diagrams below for examples
using discrete transistors or optocouplers for driving relays. The readily
available ULN2003 relay driver is specifically intended for this application
and requires no additional resistors or
diodes and can be used for relays up
to 24V.
You may wish to use multi-channel
relay modules intended for use with
Relay Polarity Setting
Install for
Active Low
Remove for
Active Hi
Arduino, Raspberry Pi and similar microcontrollers. These cards are available in 1, 2, 4, 8 and 16 channels with
5V or 12V relays and are directly compatible with the ACM outputs. Modules
are available with either active high or
active low logic inputs and if you use
multiple modules, all must be the same
Using Transistor Relay Drivers
• NPN switching transistors such as
2N2222, 2N3904, 2N4401, BC548,
or BC338 work well for small control
• Use Active High setting (jumper off)
• Flyback diode on relay coil required,
use 1N914 or 1N4148 for small relays, 1N4001 type for larger relays
Using Opto-Couplers
Using IC Drivers
ULN2003 Info
• ULN2003 provides 7 driver channels
in each 16 pin package
• Internal resistors and diodes mean
no extra components required
• Use Active High setting (jumper off)
Active High Connection
Using Relay Modules
• 4N33, H11 or PC817 types work well
for small control relays
• Commonly available modules use 4pin opto-couplers for relay drivers
• Flyback diode on relay coil required,
use 1N914 or 1N4148 for small relays, 1N4001 type for larger relays
• Use active high or active low configuration which matches the module
• Remove any module jumpers connecting relay power to logic circuits
• Can totally isolate turntable from relay power circuits
• Can be wired for either active lo or
active high configurations
Active Low Connection
• Module input common connects to
ACM COM for active high, and to
ACM +V for active low
• Relay power - connection to ACM
COM is permissible
Opto-coupler Connections
• Never connect relay power + to any
ACM pin
4 pin
6 pin
• Double check before applying power!
The ACM Serial Port is fully optically
isolated digital logic level serial I/O port
and compatible with both 3.3V and 5V
devices. The ACM signals can be connected directly to the serial RX/TX pins
on Arduino, Raspberry Pi and similar
microcontrollers, and with appropriate
adapters to standard serial or USB
ports on PC, laptop, or tablet type computers.
Communication uses plain, human
readable ASCII text messages allowing
easy programming and debugging of
your control program. All turntable
control functions are available including
programming as well as the ability to
directly control the bridge by index position in addition to the normal track
numbers. Thus all turntable programming and control functions can be offloaded to your remote device to any
extent you require.
Communication with the ACM is at
9600 baud, 8 bit, no parity , and 1 stop
bit. Both RX and TX use normal logic
polarity, ie idle state is high. Software
or hardware handshake is not supported. The serial I/O is always enabled, and there are no jumpers or
configuration needed.
Connect the GND and +5V to the external device’s ground and +5V pins.
Note the serial i/o power always connects to +5V regardless of the logic
levels in use. The ACM TX output connects to the external device RX input
and requires a pull-up to the receiver
+Vdd logic power.
usually have an internal pull-up which
can be used for this, but if not a resistor of 2-10K may be used.
The external TX output connects to the
ACM –RX pin. Connect the +RX pin to
the transmitter’s +Vdd (3.3V or 5V). It
is permissible to ground the -RX pin
and drive the +RX pin with inverted
data if required.
The 6-pin ACM Serial I/O connector is
also pin compatible with the popular
FTDI based serial adapters such as the
Adafruit FTDI Friend pictured. When
using an FTDI based device, pin 6
must be configured to be held at +5V
to provide the current source for the
RX opto-coupler LED.
based devices have option jumpers for
this pin, and can be setup to connect it
to pin 3 (+5V). If configured as the
RTS output and you have access to
the FTDI configuration, RTS can be
held false, which is high (+5). However, the standard device drivers used
by PCs and Linux computers do not
have the ability to set RTS false and
operate normally so jumpering pin 6 to
+5V is a quick and easy solution and
allows the standard drivers to communicate with the ACM.
first send a character string to the
serial port will echo
all characters by
default, so receiving
the same characters
as sent indicates
your transmit and
receive functions are working normally.
The ACM communicates using alphanumeric characters in formatted strings
as shown in the command list table
listed in Appendix C. A command
string begins with an exclamation mark
(!, dec 33) followed by an alpha command and one or more optional alphanumeric parameters, each delineated
by one or more spaces, and terminated
by a carriage return (dec 13).
The ACM will ignore all characters received before the “!” and after the carriage return, however all characters are
echoed when enabled.
The ACM response to a command
string will be preceded with a # (dec
35) and terminated with a carriage return. The ACM will respond to all command strings with either the expected
response or an error message if the
command cannot be parsed or a parameter is missing or invalid.
If a timeout error is returned to a Run,
Stop, or Home command, check the
turntable status before resending as
the error may be related to the command response from the turntable and
not the execution of the command itself.
In normal operation, wait for a response from the ACM before sending
the next command.
Attempting to
overlap transmissions may prevent the
prior command from completing normally.
Appendix D contains additional information regarding programming tracks
for those who wish to provide a complete control solution or replace the
standard control boxes completely with
a serial i/o port connection.
Appendix E lists error messages which
may also appear on the ACM digital
display when a serial port error occurs.
The ACM supports five different operating modes for up to 24 switch or
button track inputs. Each input also
supports connection of an LED which
can be used to indicate the current or
selected track in lieu of or in addition
to the digital track display.
The input mode is selected by inserting the option jumper at the desired
position on the option header block.
If switch inputs are not used, the
jumper should be placed in the disabled position. The track indicator
LEDs will function in all modes except
Keypad and while disabled.
Consult the pertinent section below
for details on how to make connections for the mode you wish to use.
All switches and LEDs connect to the
SW/LED and Function Control headers as shown in the Connecting
Switches and LEDs section.
Review the Track Input and Relay
Numbering section and be certain
you understand how the switch contact numbers correspond to service
track numbers. The assignments will
not reflect any additions, deletions or
changes made by the turntable controller or serial input until the next
power cycle occurs or a reset command is received by the serial port.
Some custom panel examples are
shown on page 12. Many other configurations are possible and limited
only by your imagination. If you are
replacing an existing turntable using
an older control system, the switch or
pushbutton modes can allow you to
use the existing control panel
switches and indicators with your new
Cornerstone® Turntable.
You should keep a standard control
box connected, or readily available as
the programming and home reset func-
Control Panel Options
tions are not available in all modes.
Control Box mode emulates the standard control box and all functions are
available. Keypad mode will accept
track 0 as an entry and perform the
home reset. The other options do not
have access to the programming and
reset functions.
Connect five pushbutton switches to
the CW, CCW, Head, Tail and Track
terminals on the Function Switch
header to use the ACM as a standard
control box. In this mode, all turntable
control functions are available as listed
in the turntable instructions, including
programming and home reset. You
may use either the digital display readout or individual track indicator LEDs
for position feedback. Note that the
track selection is not limited to the 24
count limit, although the track indicator
LEDs will be.
Control Box mode allows the standard
control functionality to be built into a
control panel in any configuration desired, especially where you may not
have room for the standard control box.
Control Box Operation
• Push Track button
• Push CW & CCW to select track
• Push Track for closest move, or
Head or Tail to specify end to align
• For Turn function, push Head or Tail
to reverse bridge at current location
• See turntable instructions for a comlete list of commands
Pushbutton mode uses a momentary
pushbutton for selecting tracks and
specifying the head, tail and closest
end to begin rotation.
Pushbutton Operation
• Push button for desired track
• Push Head, Tail, or Closest button to
initiate rotation
This option works well with the
switches arranged on a graphic image
of the service track layout or in a linear
list such as those shown in the Custom
Control Panel Examples section. Connect track indicator LEDs as shown for
each track selection. The LEDs will
flash to indicate a new selection is being made, as well as when the turntable bridge is in motion. Note that the
LEDs will also react to commands
which are entered via any standard
control boxes which may also be present in the turntable control circuit.
• For Turn, push Head or Tail button
Be certain to read the Track Input and
Relay Numbering section for information on how track input terminals correspond to service track numbers. Note
that any changes made to service track
numbers may cause the switch assignments to change on the next power
Switch Input mode uses a maintained
contact such as a rotary selector switch
or set of radio type latching pushbuttons to select the desired track. A
SPDT toggle is used to specify the
bridge end to align, and movement is
initiated with a ‘Run’ pushbutton connected to the track terminal. Older
turntable control systems typically used
this type of switch input for track selection, and this option allows an existing
turntable control panel to be used. Up
to 24 contacts are supported.
Switch Operation
• Use switch to select desired track
• Select Head or Tail, or center off for
closest move
• Push ‘Run’ button to initiate rotation
• For Turn, select opposite end with
Head/Tail switch and push ‘Run’
with another control box, or a new track
or end is selected but the move not
Optional LEDs may be used to indicate
track selection as shown in the diagram. Note that if the current bridge
position does not match the switch positions, the LEDs will not illuminate.
This may occur if the bridge is moved
Use of a center-off type toggle will allow the closest move option to be
A digital rotary encoder such as those
shown here allows a track to be quickly
selected by rotating the knob and
pushing a button. These devices offer
continuous rotation and typically have
16 to 20 detents per
rotation to allow precise selection.
Many encoders
have an integral
switch which is
handy for the Track connection. If your
encoder does not have an imbedded
switch, you will need to add a third
pushbutton if you wish to use the closest move option.
The encoder A & B outputs are sequenced in a manner that allows the
ACM to determine the direction of rotation and increment or decrement the
selection accordingly.
Connect the encoder outputs as shown
with the CW input leading CCW for
Encoder Operation
• Rotate Encoder to desired track
• Push Encoder switch for closest
move, or Head or Tail to specify end
to align
• For Turn function, push Head or Tail
to reverse bridge at current location
clockwise rotation. If the track selections move in the wrong direction, reverse the A & B connections to CW &
You may use either the numeric display or track LEDs for selection indication.
A standard 3x4
or 4x4 matrix
keypad may be
used to allow
direct input of
track numbers to
control turntable operation. You may
wish to use a commonly available unit
such as those shown, or you can construct your own from individual
pushbuttons connecting a row and column as shown in the diagram. The
matrix rows are connected to SW inputs 1-4 and the columns to inputs 5-8
as shown. The Keypad can access
any defined service track and is not
subject to the 24 count limit, and thus
may be preferred for those installations
Keypad Operation
• Enter 1 or 2 digit track number
• Push Head or Tail to initiate rotation
• H/T makes closest move to track
• Turn may use dedicated button or
use Head or Tail without entering a
track number
• CW & CCW button may be used to
manually move bridge to next track
after release, same as standard control box
having a very large number of service
tracks as the desired track number can
be directly entered rather than picked
from a list or diagram.
Momentary pushbuttons
connect a row to a column
Appendix A — Display Brightness Setting
The ACM digital display and track indicator LED intensity is adjustable via an
internal Brightness setting in a manner
similar to the turntable standard control
box. The range is 1 (dimmest) to 9
(brightest), and has a default level of 5.
Note the ACM uses constant current
drivers for the LEDs and series resistors
cannot be used to set the display level.
If you have the serial port connected,
the level can be adjusted directly at any
time with the ‘Bright’ command.
For the other input options you will need
to use the switches connected to the
CW, CCW, Head/Tail, and Track terminals on the Function Switch header to
adjust the setting. If these switches are
not included on your custom panel, such
as Keypad, connect a temporary set of
switches to the terminals to make the
setting, which can be removed when
When using the Encoder option, set the
option jumper to Control Box to make
If you are using the ‘Control Box’ switch the adjustment, then return to Encoder
when done. You may need to disconoption, the brightness adjust procedure
nect the encoder outputs from the CW
for the standard control box can be used
and CCW terminals as well, depending
to set the level. See the turntable inon the encoder in use.
struction sheet for details.
Follow the steps listed to set the bright-
Setting Brightness Level
• Push and hold CW or CWW and
apply power
• Continue to hold button until bx display appears
• Use CW and CCW to increment or
decrement display to new setting
• Push Track button to save the new
• Push Head or Tail to cancel and revert to old setting
ness level. Once set, the level is stored
internally and restored on power-up. An
ACM Reset sent to the serial port will
not change the brightness value.
Appendix B — Display Error Codes
Position Reference
Pit Controller error
Home reference location could not be restored, reset required
Home Sensor Not Found
Pit Controller error
Home sensor my be blocked, bad pit LED, bad bridge sensor
Communication Error
Pit Controller error
Bridge wiper intermittent, bad control cable
Bridge Not Responding
Pit Controller error
Bridge is not installed, bad bridge wipers
Configuration Error
Pit Controller error
Internal configuration info bad, factory reset may clear
Configuration Error
ACM error
More than 4 control devices connected, remove one
Pit Not Responding
ACM error
Pit controller not running, bad control cable
Internal Memory Error
Pit Controller error
Internal ROM memory failure, fatal error
Low Supply Voltage
Pit Controller error
12-18 VAC / 16-24 VDC required for turntable operation
Invalid Track Number
ACM error
Track number is not defined
E0 Position Error can be cleared by pushing any key. Service track locations will not be correct until a
reset of the home position is done. Other errors will clear automatically when the cause is corrected.
Appendix C— Serial Port Commands
• 9600 baud, 8 bit, no parity, 1 stop bit, handshake not supported
• Syntax, delimited with one or more spaces: ! cmd parm1 parm2 <CR>
• Alpha numeric characters only: a-z, A-Z, 0-9
• Alpha commands and parameters may be abbreviated as shown in bold
• Use of leading zeros in numeric parameters is permitted
• Optional parameters denoted with ( )
• General acknowledgement is “#OK: “ followed by parsed command string if no error
• All characters before the ! and after <CR> are ignored but echoed (if enabled)
Serial I/O Commands
Rotates bridge in specified direction
Rotates bridge head to index position xxxxx using shortest direction
Rotates bridge CW to the home position
Immediately stops bridge rotation
Stops bridge at next track in direction of rotation
Stops bridge at index location xxxxx
Rotates bridge CW to the home position (same as RUN HOME)
Turns character echo on or off
Sets / Returns the display brightness level 1-9, default is 5
Returns status string: #INFO: n dir position track end
n - bridge speed 0-3, 0 is stopped
dir - current or last bridge direction CW or CC
position - current bridge head location
track - current or target track, “- - “ if none
end - current or target end
Returns current Auto setting #AUTO: n
Starts automatic info transmit at nnn/10 per second, nnn = 0-250
On sets to 1/sec ( AUTO 10 ), Off stops info transmits ( AUTO 0 )
Restarts ACM (same as a power up)
Reverses bridge at current location
Returns current or target track number, “- -” if none
Returns current bridge location #LOCATION: xxxxx
Returns maximum value for position index #MAX: xxxxx
Returns position index for track nn #LOCATION nn xxxxx
Rotates to specified track, uses closest move if parm2 is null
Returns position index of next track larger than nn
If nn = 0, returns index for lowest numbered track
If nn is null, returns index for next track after previous nn
Returns 0 if no track larger than nn is programmed
Returns target position index #TARGET: xxxxx
Sets / Returns decoder address dddd for track nn #DCC: nn dddd
Sets / Returns decoder address dddd for turn function
Sets position index for track nn to xxxxx or current index if null
Deletes position index definition for track nn
Appendix D — Serial Port Track Programming
If you wish to program turntable service
tracks via the serial port, follow the procedure below to retain the turntable controller’s ability to accurately position the
bridge at the desired track location.
track, it is also necessary to account for
gear backlash in the bridge motor
drivetrain and approach the stop position from the same direction as used
when setting the track location. The
controller uses the parity of the count
The turntable controller relates the
assigned to a track number to indicate
bridge head position to the home sensor
the required alignment direction. When
location by keeping track of an index
count as the bridge rotates. The abso- the location is an odd number, the final
alignment is clockwise, and when even
lute number of counts is related to the
bridge motor gearing as well as the size
of the turntable and differs for each of
When a Run xxxxx command is sent,
the turntable models. The Location Max the controller calculates the direction of
command returns the value in use. The rotation required for the shortest move
total number of counts allows rotational and automatically includes an overrun
resolution to better than .01 degree any- and reverse move when necessary to
where on the pit circumference.
perform the final alignment in the proper
The controller is capable of stopping the direction based on the commanded tarbridge within a very small count window get position.
at any arbitrary location. As the bridge
rotates, the count increments for clockwise rotation and decrements for
counter-clockwise, rolling over at the
home sensor which is located at the
max count position. Thus the first count
clockwise from the home position is 1,
the first counter-clockwise is max-1.
When aligning the bridge to a service
The Program nn xxxxx command associates count position xxxxx with track nn.
The stored count value is the head location and should be incremented or decremented to correct the parity to match
the direction of last movement before
saving. The Info command returns the
direction of last movement when the
bridge is stopped, which can relieve
your external program from keeping
track of it.
The index count always defines the location of the bridge head end, and the
location of the tail is calculated by adding or subtracting max / 2 from the current location and correcting the result if
necessary to maintain the parity.
Track definition changes made via the
serial port are effective immediately
As an example executing a Run 10000 however it is necessary to execute a
command from location 1000 will cause Reset ACM command or a power-up
the bridge to rotate clockwise and percycle to reinitialize the ACM relay drivers
form a reverse alignment before stopand switch inputs to include the upping as the target count is an even num- dates. Note that terminal number to
ber. Using Run 10001 or Run 9999 will track number relationships on the ACM
result in the same move without the re- connector headers may change dependverse alignment as the bridge is already ing on the new active track numbers.
moving in the correct direction.
Appendix E — Serial Port Error Codes
Err 1
Parameter Out of Range
Numerical parameter is not valid
Err 2
Command Format Error
Command string cannot be parsed or bad syntax
Err 3
ACM Busy
Command cannot be executed, retry
Err 4
Buffer Overflow
Command buffer length exceeded
Err 5
Command Timeout
Pit controller response timeout - Check status before resending
Err 6
Turntable Busy
Pit controller busy, command ignored
Err 7
Invalid Track Number
Track number is not defined
Err 8
Invalid Command
Command is not defined
Err 9
Command Ignored
Command not executed, may be redundant
Err A
Invalid Parameter
Parameter is not defined or may be bad syntax
Error responses are followed by the parsed command string. ACM will respond to any character string sent between the ! and <CR>
with the defined command response or an error message defined above.
An easy to use control panel can be
setup using a graphic image of the
turntable service tracks. Here an LED
illuminated pushbutton is used for each
of the service tracks and the Head and
Tail inputs. A non-illuminated button
on the Track input is located at the
center of the bridge to select the closest move option.
The graphic image also works well using a rotary encoder at the center position for track selection. LEDs are used
to indicate the selected track, and the
encoder push switch connects to the
Track terminal for the closest move
In both cases the Turn function is accessed by using the unlit end button to
swap the bridge ends at the current
Use of numbered indicators is optional
as the graphic image conveys the position information.
Railroads frequently refer to tracks by
name or function, rather than by number. A control panel can be set up using a list of track names with indicators
to show the current or selected location
as shown here. The head and Tail
buttons are also illuminated to show
the bridge orientation.
The Control Box mode Up/Down,
Head/Tail and Track input buttons can
be used to scroll the selection up or
down the list and motion initiated with
the Head, Tail, or Track buttons.
The control functions in Control Box
Mode are the same as the standard
control box, and the list will scroll thru a
‘none’ selection (meaning track 0) for
Encoder input mode also works well
with a list of service track names as
shown here. The encoder is used to
scroll up and down to the desired track,
and the Head or Tail button used to
initiate the motion.
then pushing the encoder knob to initiate the movement. With an engine on
the bridge, the Head or Tail buttons
would normally be used to specify the
bridge end to align to the selected
Encoders with an integrated push
switch can be used, connecting the
encoder button to the Track input terminal. In encoder mode the Track input functions as a ’closest move’ command, which causes the bridge head or
tail to align to the selected track, whichever is closest.
Any other variation of the panels
shown here can be used, and features
can be mixed and matched as your
particular needs require. The numeric
digital display can be used with any of
these examples if desired in addition to
the track indicator LEDs.
With the bridge empty, a service track
can be selected simply by rotating the
encoder to select the desired track,
Custom panels based on the ACM may
be used simultaneously with one or
more standard control boxes if multipoint control is a requirement.
access to the turntable home reset
The Turn Function is available by selecting Head or Tail button first to swap
ends of the bridge at the current track
The Control Box mode has the same
functionality as the standard control
box, so using a custom version retains
the home reset function as well as the
ability to control the bridge manually
using the Up/Down (CW/CCW) buttons.
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