4 F4-04ADS 4-Channel Isolated Analog Input

4 F4-04ADS 4-Channel Isolated Analog Input
F4-04ADS
4-Channel
Isolated Analog Input
In This Chapter. . . .
Ċ Module Specifications
Ċ Setting the Module Jumpers
Ċ Connecting the Field Wiring
Ċ Module Operation
Ċ Writing the Control Program
4
4–2
F4-04ADS 4-Channel Isolated Analog Input
Module Specifications
ANALOG
The F4-04ADS 4-Channel Isolated Analog Input
module provides several features and benefits.
S It accepts four differential voltage or
current inputs.
S Inputs have channel-to-channel
isolation.
S Analog inputs are also optically isolated
from PLC logic components.
S The module has a removable terminal
block, so the module can be easily
removed or changed without
disconnecting the wiring.
INPUT
F4–04ADS
0–10VDC
0–5VDC
4mA–20mA
CH1
C
CH2
C
CH3
C
CH4
C
CH1
+V
CH1
R
CH2
+V
CH2
R
CH3
+V
CH3
R
CH4
+V
CH4
R
24VDC 0.5A
0
V
F4–04ADS
4-Ch. Isolated Analog In.
Analog Input
Configuration
Requirements
24
V
The F4–04ADS Analog Input module requires 16 discrete input points from the
CPU. The module can be installed in any slot of a DL405 system, including remote
bases. The limitations on the number of analog modules are:
S For local and expansion systems, the available power budget and
discrete I/O points.
S For remote I/O systems, the available power budget and number of
remote I/O points.
Check the user manual for your particular model of CPU for more information
regarding power budget and number of local or remote I/O points.
4–3
F4-04ADS 4-Channel Isolated Analog Input
The following tables provide the specifications for the F4-04ADS Analog Input
Module. Review these specifications to ensure the module meets your application
requirements.
Input
Specifications
General
Specifications
4
Input Ranges
0–5V, 0–10V, 1–5V, $5V, $10V,
0–20 mA, 4–20 mA
Resolution
12 bit (1 in 4096)
Conversion Method
Successive approximation
Input Type
Differential
Max. Common Mode Voltage
$750V peak continuous transformer isolation
Noise Rejection Ratio
Common mode: –100 dB at 60Hz
Active Low-Pass Filtering
–3 dB at 20Hz, –12 dB per octave
Input Impedance
250W $0.1%, 1/2W current input
200KW voltage input
Absolute Maximum Ratings
$45 mA, current input
$100V, voltage input
Conversion Time
1 mS per selected channel
Linearity Error
$1 count (0.025% of full scale) maximum
Full Scale Calibration Error
$8 counts maximum (Vin = 20 mA)
Offset Calibration Error
$8 counts maximum (Vin = 4 mA)
PLC Update Rate
4 channel per scan max.
Digital Input Points Required
12 binary data bits, 4 active channel
indicator bits
Accuracy vs. Temperature
$100 ppm / _C maximum full scale (including
maximum offset)
Power Budget Requirement
270 mA @ 5 VDC (from base)
External Power Supply
24 VDC, $10%, 120 mA, class 2
Recommended Fuse
0.032 A, Series 217 fast-acting, current
inputs
Operating Temperature
0 to 60_C (32 to 140°F)
Storage Temperature
–20 to 70_C (–4 to 158° F)
Relative Humidity
5 to 95% (non-condensing)
Environmental air
No corrosive gases permitted
Vibration
MIL STD 810C 514.2
Shock
MIL STD 810C 516.2
Noise Immunity
NEMA ICS3–304
F4–04ADS
4-Ch. Isolated Analog In.
Number of Channels
4–4
F4-04ADS 4-Channel Isolated Analog Input
Setting the Module Jumpers
Jumper
Locations
The module has several options that you can select by installing or removing
jumpers. At the rear of the module are three banks of jumpers:
S One bank of 16 jumpers, which may be configured to select the number
of channels enabled, channel range (for channels 1–4), and polarity.
S Two banks of four jumpers; one bank to set the offset voltage for
channels 1 and 2, and the other bank to set the offset voltage for
channels 3 and 4.
Also included are four additional jumpers to use as needed; each jumper is stored
over a single pin on the Channel 3 and Channel 4 ranges (this is a good way to store
unused jumpers so they do not get lost).
Voltage Offset
for each channel
Ch 1
Ch 2
1V 0V 1V 0V
0
F4–04ADS
4-Ch. Isolated Analog In.
Number of
Channels
Factory Default
Settings
1
Extra
Jumpers
Ch 3
Ch 4
1V 0V 1V 0V
BI Uni 1/2
1
2 1/2
Polarity Channel 1
Range
By default, the module arrives
from the factory with the
jumpers installed or removed
as shown here.
With these jumper settings the
module is setup as follows:
S With four active
channels.
S With each channel set
to 1V signal offset.
S With Unipolar polarity
mode (this setting will
apply to all active
channels).
S With 4–20mA signal
range for each
channel.
1
2
Channel 2
Range
Number of
Channels
Polarity
Channel 1
Range
0
1
Bi
Uni
½
1
2
Channel 2
Range
½
1
2
Channel 3
Range
½
1
2
Channel 4
Range
½
1
2
1/2
1
2
1/2
1
2
Channel 3 Channel 4
Range
Range
1V
0V
1V
0V
Channel 1
Offset
Channel 2
Offset
1V
0V
1V
0V
Channel 3
Offset
Channel 4
Offset
4–5
F4-04ADS 4-Channel Isolated Analog Input
Selecting the
Number of
Channels
The jumpers labeled 0 and 1 are used to
select the number of channels that will be
used. The module is set from the factory for
four-channel operation.
Any unused channels are not processed.
For example, if you only select channels 1
thru 3, channel 4 will not be active. Use the
following table to set the jumpers for your
application.
Channels Selected
0
1
Jumper Settings
Channels 1
Example Settings
Number of
Channels
0
1
Channels 1 and 2
0
1
Channels 1, 2 and 3
0
1
Channels 1, 2, 3 and 4
0
1
1V Channel 1
0V Offset
Number of
Channels
Polarity
Bi
Uni
Channel 1
Range
1/2
1
2
Channel 2
Range
Channel 3
Range
Channel 4
Range
F4–04ADS
4-Ch. Isolated Analog In.
Once you select the number of
channels, you must set the other
parameters. Use this example to
see how to set the jumpers. The
example only shows settings for
channel 1 operation, but the
procedure is the same for the other
channels.
An explanation of the example
settings is as follows:
S Number of Channels: Both
jumpers are removed for
one-channel operation.
S Polarity: The jumper is set for
Bipolar (Bi) signal range (Uni
is the setting for unipolar
range).
S Channel 1 Offset: The jumper
is set for 0V offset.
S
Channel 1 Range: The
jumper is set to “2”, which is
$2.5 VDC ($10mA) when
Bipolar signal range is
selected (see the tables on
the following page for more
information).
4–6
F4-04ADS 4-Channel Isolated Analog Input
The following tables show the jumper selections for the various ranges. Only
channel 1 is used in the example, but all the channels must be set. You can have a
combination of offsets and ranges but not polarities for each of the channels. For
example, if the polarity is set for unipolar signal range, this setting will apply to all
active channels.
Bipolar Signal Range
$2.5 VDC
($10 mA)
Jumper Settings
Ch 1
1V 0V
Channel 1 Ranges
1/2
$5 VD
($20 mA)
Ch 1
1V 0V
Ch 1
1V 0V
F4–04ADS
4-Ch. Isolated Analog In.
4 to 20 mA
(1 VDC to 5 VDC)
Ch 1
1V 0V
1
2
Channel 1 Ranges
Ch 1
1V 0V
Ch 1
1V 0V
1
2
Channel 1 Ranges
1/2
0 VDC to +10 VDC
2
BI
UNI
Polarity
BI
UNI
Polarity
BI
UNI
Jumper Settings
1/2
0 VDC to +5 VDC
(0 to +20 mA)
1
Channel 1 Ranges
1/2
Unipolar Signal Range
2
Channel 1 Ranges
1/2
$10 VDC
1
Polarity
1
2
Channel 1 Ranges
1/2
1
2
Polarity
BI
UNI
Polarity
BI
UNI
Polarity
BI
UNI
4–7
F4-04ADS 4-Channel Isolated Analog Input
Connecting the Field Wiring
Wiring
Guidelines
Your company may have guidelines for wiring and cable installation. If so, you
should check those before you begin the installation. Here are some general things
to consider.
S Use the shortest wiring route whenever possible.
S Use shielded wiring and ground the shield at the transmitter source. Do
not ground the shield at both the module and the source.
S Don’t run the signal wiring next to large motors, high current switches,
or transformers. This may cause noise problems.
S Route the wiring through an approved cable housing to minimize the
risk of accidental damage. Check local and national codes to choose
the correct method for your application.
User Power Supply The F4-04ADS requires a separate power supply. The DL430/440/450 CPU’s,
D4-RS Remote I/O Controller, and D4-EX Expansion Units have built-in 24 VDC
Requirements
power supplies that provide up to 400mA of current. If you only have a few analog
modules, you can use this power source instead of a separate supply. If you have
already used the available current from this source, or if you would rather use a
separate supply, choose one that meets the following requirements: 24 VDC
$10%, Class 2, 120mA current.
Occasionally you may have the need to connect a transmitter with an unusual
Custom Input
signal range. By changing the wiring slightly and adding an external resistor to
Ranges
convert the current to voltage, you can easily adapt this module to meet the
specifications for a transmitter that does not adhere to one of the standard input
ranges. The following diagram shows how this works.
NOTE: Do not Jumper V & R with this procedure
V+
+
+
R
–
R=
R
Vmax
250 ohms
Imax
R = value of external resistor
Vmax = high limit of selected voltage range (5V or 10V)
Imax = maximum current supplied by the transmitter
Example: current transmitter capable of 50mA, 0 – 10V range selected.
10V
R=
R = 200 ohms
50mA
NOTE: Your choice of resistor can affect the accuracy of the module. A resistor that
has $0.1% tolerance and a $50ppm / _C temperature coefficient is
recommended.
F4–04ADS
4-Ch. Isolated Analog In.
50mA
to Analog circuitry
–
C–
4–8
F4-04ADS 4-Channel Isolated Analog Input
Current Loop
Transmitter
Impedance
Standard 4 to 20 mA transmitters and transducers can operate from a wide variety
of power supplies. Not all transmitters are alike and the manufacturers often specify
a minimum loop or load resistance that must be used with the transmitter.
The F4-04ADS provides 250 ohms resistance for each channel. If your transmitter
requires a load resistance below 250 ohms, then you do not have to make any
adjustments. However, if your transmitter requires a load resistance higher than
250 ohms, then you need to add a resistor in series with the module.
Consider the following example for a transmitter being operated from a 36 VDC
supply with a recommended load resistance of 750 ohms. Since the module has a
250 ohm resistor, you need to add an additional resistor.
R + Tr * Mr
R + 750 * 250
R – resistor to add
Tr – Transmitter Requirement
Mr – Module resistance (internal 250 ohms)
R w 500
Two-wire Transmitter
+
–
Module Channel 1
V
C
R
R
DC Supply
+36V
0V
250 ohms
Removable
Connector
The F4-04ADS module has a removeable connector to make wiring easier. Simply
remove the retaining screws and gently pull the connector from the module.
Wiring
Diagram
NOTE 1: Shields should be grounded at the signal source.
ANALOG
F4–04ADS
4-Ch. Isolated Analog In.
NOTE 2: Unused channels should have V & C & R of the channels jumpered together.
4 CHANNELS
F4–04ADS
0–10VDC
0–5VDC
1–5VDC
+10VDC
+5VDC
4–20mA
See NOTE 1
V
CH1
+
Voltage
Transmitter –
C
CH1
C
R
250 ohms
CH1
+V
CH1
R
V
See NOTE 2
CH2 Not Used
C
V
CH3
+
2-wire 4–20mA
Transmitter –
Analog
switch
R
CH2
C
250 ohms
C
R
V
CH4
+
2-wire 4–20mA
–
Transmitter
250 ohms
CH3
C
C
R
250 ohms
+
CH4
C
CH2
+V
CH2
R
CH3
+V
CH3
R
CH4
+V
CH4
R
24VDC 0.5A
–
+
–
User
Supply
21.6 - 26.4 VDC
INPUT
0
V
24
V
4–9
F4-04ADS 4-Channel Isolated Analog Input
Module Operation
DL430 Special
Requirements
Even though the module can be placed in any slot, it is important to examine the
configuration if you are using a DL430 CPU. As you can see in the section on writing
the program, you use V-memory locations to extract the analog data. As shown in
the following diagram, if you place the module so that the input points do not start on
a V-memory boundary, the instructions cannot access the data.
F4–04ADS
Correct!
8pt
Input
8pt
Input
16pt
Input
X0
–
X7
X10 X20 X40
–
–
–
X17 X37 X57
V40400
16pt
Input
16pt
Output
16pt
Output
V40402
V40401
MSB
X
3
7
LSB
XX
3 2
0 7
X
2
0
F4–04ADS
Wrong!
16pt
Input
8pt
Input
16pt
Input
X0
–
X7
X10 X30 X40
–
–
–
X27 X37 X57
16pt
Output
16pt
Output
Data is split over two locations, so instructions cannot access data from a DL430.
MSB
X
3
7
V40401
XX
3 2
0 7
LSB
X
2
0
MSB
X
1
7
V40400
XX
1 7
0
LSB
X
0
F4–04ADS
4-Ch. Isolated Analog In.
8pt
Input
4–10
F4-04ADS 4-Channel Isolated Analog Input
Channel
Scanning
Sequence
Before you begin writing the control program, it is important to take a few minutes to
understand how the module processes and represents the analog signals.
The F4-04ADS module supplies one channel of data per each CPU scan. Since
there are four channels, it can take up to four scans to get data for all channels.
Once all channels have been scanned the process starts over with channel 1.
Unused channels are not processed, so if you select only two channels, then each
channel will be updated every other scan.
Scan
Read Inputs
Scan N
Channel 1
Scan N+1
Channel 2
Scan N+2
Channel 3
Scan N+3
Channel 4
Scan N+4
Channel 1
Execute Application Program
Read the data
F4–04ADS
4-Ch. Isolated Analog In.
Store data
Write to Outputs
Even though the channel updates to the CPU are synchronous with the CPU scan,
the module asynchronously monitors the analog transmitter signal and converts
the signal to a 12-bit binary representation. This enables the module to
continuously provide accurate measurements without slowing down the discrete
control logic in the RLL program.
4–11
F4-04ADS 4-Channel Isolated Analog Input
Input Bit
Assignments
The F4-04ADS module requires 16 discrete input points from the CPU. These 16
points provide:
S an indication of which channel is active.
S the digital representation of the analog signal.
Since all input points are automatically mapped into V-memory, it is very easy to
determine the location of the data word that will be assigned to the module.
F4-04ADS
8pt
Input
8pt
Input
16pt
Input
16pt
Input
X0
–
X7
X10 X20 X40
–
–
–
X17 X37 X57
V40400
MSB
16pt
Output
V40402
V40401
Bit 15 14 13 12 11 10 9
X
3
7
16pt
Output
8
7
X X
3 2
0 7
LSB
6
5
4
3
2
1
0
X
2
0
Within this word location, the individual bits represent specific information about the
analog signal.
The last four bits (inputs) of the upper
V-memory location indicate the active
channel. The inputs are automatically
turned on and off to indicate the current
channel for each scan.
Channel
Scan
Bits
Channel
N
0001
1
N+1
0010
2
N+2
0100
3
N+3
1000
4
V40401
MSB
LSB
1 1 1 1 1 1 9 8 7 6 5 4 3 2 1 0
5 4 3 2 1 0
– active channel inputs
F4–04ADS
4-Ch. Isolated Analog In.
Active Channel
Indicator Inputs
4–12
F4-04ADS 4-Channel Isolated Analog Input
Analog Data Bits
The first twelve bits represent the analog
data in binary format.
Bit
Value
Bit
Value
0
1
6
64
1
2
7
128
2
4
8
256
3
8
9
512
4
16
10
1024
5
32
11
2048
V40401
MSB
LSB
1 1 1 1 11 9 8 7 6 5 4 3 2 1 0
5 4 3 2 10
– data bits
Since the module has 12-bit resolution, the analog signal is converted into 4096
counts ranging from 0 – 4095 (212). For example, with a 0 to 10V scale, a 0V signal
would be 0, and a 10V signal would be 4095. This is equivalent to a binary value of
0000 0000 0000 to 1111 1111 1111, or 000 to FFF hexadecimal. The following
diagram shows how this relates to each signal range.
–10V to +10V
–5V to +5V
+V
+V
0V to 10V
0V to 5V
1V to 5V
4 to 20mA
+5V
20mA
1V
4mA
0V
–V
0V
F4–04ADS
4-Ch. Isolated Analog In.
0
4095
0
4095
0
Each count can also be expressed in
terms of the signal level by using the
equation shown. The following table
shows the smallest signal change that
will result in a single LSB change in the
data value for each signal input range.
Range
4095
0
4095
Resolution + H * L
4095
H = high limit of the signal range
L = low limit of the signal range
Signal Span
(H – L)
Divide By
Smallest Detectable
Change
$10V
20 V
4095
4.88 mV
$5V
10 V
4095
2.44 mV
0 to 5V
5V
4095
1.22 mV
0 to 10V
10 V
4095
2.44 mV
1 to 5V
4V
4095
0.98 mV
16 mA
4095
3.91 mA
4 to 20mA
4–13
F4-04ADS 4-Channel Isolated Analog Input
Writing the Control Program
Multiple
Channels
Selected
Once you have configured the F4–04ADS module, use the following examples to
get started writing the control program.
Since all channels are multiplexed into a single data word, the control program must
be setup to determine which channel is being read. Since the module appears as X
input points to the CPU, it is very easy to use the active channel status bits to
determine which channel is being monitored.
F4–04ADS
8pt
Input
X0
–
X7
8pt
Input
16pt
Input
16pt
16pt
16pt
Input Output Output
X10 X20 X40
–
–
–
X17 X37 X57
V40400
V40402
V40401
MSB
LSB
Active
Channel Bits
Reading Values,
DL440/450
5 4 4
430 440 450
Data Bits
This program example shows how to read the analog data into V-memory locations
with DL440/DL450 CPUs. Once the data is in V-memory, you can perform math on
the data, compare the data against preset values and so forth. This example reads
one channel per scan, so it takes four scans to read all four channels.
LDF
K12
BCD
X34
X35
X36
X37
X20
Loads the first 12 bits of the data word into the accumulator (starting
with location X20).
Converts the binary value in the accumulator to BCD and stores the
result in the accumulator. It is usually easier to perform math
operations in BCD, so it is best to convert the data to BCD
immediately. You can leave out this instruction if your application
does not require it. Do not use this instruction if you are going to
send the data to an internal PID loop because the PID loop requires
the PV (process variable) to be in binary format.
OUT
V3000
When contact X34 is on, channel 1 data is being sent to the CPU.
The OUT instruction moves the data from the accumulator to V3000.
OUT
V3001
When contact X35 is on, channel 2 data is stored in V3001.
OUT
V3002
When contact X36 is on, channel 3 data is stored in V3002.
OUT
V3003
When contact X37 is on, channel 4 data is stored in V3003.
Note, this example uses SP1, which is always on and the
inputs are continually being updated. You could also use an
X, C, etc. permissive contact.
F4–04ADS
4-Ch. Isolated Analog In.
SP1
4–14
F4-04ADS 4-Channel Isolated Analog Input
Reading Values,
DL430
4 4 4
430 440 450
The following program example shows how to read the analog data into V-memory
locations with the DL430 CPU. Since the DL430 does not support the LDF
instruction, you can use the LD instruction instead as shown. The example also
works for DL440 and DL450 CPUs. This example will read one channel per scan, so
it will take four scans to read all four channels.
SP1
LD
V40401
Loads the complete data word into the accumulator. The V-memory
location depends on the I/O configuration. See Appendix A for the
memory map.
ANDD
KFFF
ANDs the value in the accumulator with the constant KFFF, which
masks the channel identification bits, and stores the vaue in the
accumulator. Without this, the values used will not be correct, so do
not forget to include it.
BCD
X34
X35
X36
F4–04ADS
4-Ch. Isolated Analog In.
X37
Converts the binary value in the accumulator to BCD and stores the
result in the accumulator. It is usually easier to perform math
operations in BCD, so it is best to convert the data to BCD
immediately. You can leave out this instruction if your application
does not require it. Do not use this instruction if you are going to
send the data to an internal PID loop because the PID loop requires
the PV (process variable) to be in binary format.
OUT
V3000
When contact X34 is on, channel 1 data is being sent to the CPU.
The OUT instruction moves the data from the accumulator to V3000.
OUT
V3001
When contact X35 is on, channel 2 data is stored in V3001.
OUT
V3002
When contact X36 is on, channel 3 data is stored in V3002.
OUT
V3003
When contact X37 is on, channel 4 data is stored in V3003.
Note, this example uses SP1, which is always on and is
continually being updated. You could also use an X, C, etc.
permissive contact.
Single Channel
Selected
4 4 4
430 440 450
Since you do not have to determine which channel is selected, the single channel
program is even more simple.
X34
LD or LDF
BCD
OUT
V3000
When X34 is on, channel 1 data is being sent to the CPU. Use the
LD instruction when using a DL430 CPU.*
The BCD instruction converts the data from binary to BCD.
You can leave out this instruction if your application does not
require it.
The OUT instruction stores the data in V3000.
* Remember, before the BCD instruction is executed, the DL430 requires an additional
instruction to mask out the first four bits that are brought in with the LD instruction. An example
of how to do this using an ANDD instruction is shown in the previous section.
4–15
F4-04ADS 4-Channel Isolated Analog Input
Reading Four
Channels in
One Scan,
DL440/450 Only
5 4 4
The following program shows you how to read all four channels in one scan by using
a FOR/NEXT loop. Remember, this routine will lengthen the scan time. If you do not
need to read the analog data on every scan, change the SP1 to a permissive
contact (such as X input, CR, or stage bit) to only enable the loop when it is required.
430 440 450
NOTE: Do not use this FOR/NEXT loop program to read the module in a
remote/slave arrangement; it will not work. Use one of the programs that reads one
channel per scan.
K4
SP1
FOR
SP1
LDIF X20
K12
Starts the FOR/NEXT loop. The constant (K4) specifies how many
times the loop will execute, equal to the number of channels you are
using. For example, enter K3 if you are using 3 channels.
Loads immediate 12 bits of the data word into the accumulator. The
LDIF instruction retreives the I/O points without waiting for the CPU
to finish the scan.
Changes the value in the accumulator to BCD. You can leave this out
if it is not required (such as for PID loops).
BCD
LDIF X34
K4
ENCO
NEXT
The ENCO instruction encodes the bit position in the accumulator
having a value of 1, and returns the corresponding binary
representation.
The OUTX instruction copies a 16 bit value from the accumulator to
V3000.
One of the four active channel bits will be on each time through the
FOR/NEXT loop, indicating the active channel. The corresponding
OUT instruction places the 12 or 16-bit value in the accumulator in
the proper V-memory location.
Note: This example uses SP1, which is always on. You could also use an X, C, etc. permissive contact.
Scaling the Input
Data
Most applications usually require
measurements in engineering units,
which provide more meaningful data.
This is accomplished by using the
conversion formula shown.
You may have to make adjustments to
the formula depending on the scale you
choose for the engineering units.
Units + A H * L
4095
H = high limit of the EU range
L = low limit of the EU range
A = Analog value (0 – 4095)
For example, if you wanted to measure pressure (PSI) from 0.0 to 99.9 then you
would have to multiply the analog value by 10 in order to imply a decimal place when
you view the value with the programming software or a handheld programmer.
Notice how the calculations differ when you use the multiplier.
F4–04ADS
4-Ch. Isolated Analog In.
OUTX
V3000
Loads immediate 4 bits of the data word into the accumulator. The
LDIF instruction retreives the I/O points without waiting for the CPU
to finish the scan.
4–16
F4-04ADS 4-Channel Isolated Analog Input
Analog Value of 2024, slightly less than half scale, should yield 49.4 PSI
Example without multiplier
Units + A H * L
4095
Units + 2024 100 * 0
4095
Example with multiplier
Units + 10 A H * L
4095
Units + 20240 100 * 0
4095
Units + 49
Units + 494
Handheld Display
Handheld Display
V 3101 V 3100
V MON 0000 0049
V 3101 V 3100
V MON 0000 0494
This value is more accurate
Here is how you would write the program to perform the engineering unit
conversion.
Note, this example uses SP1, which is always on. You
could also use an X, C, etc. permissive contact.
SP1
LDF X20
K12
BCD
F4–04ADS
4-Ch. Isolated Analog In.
X34
X1
OUT
V3000
Loads the data word into the accumulator. The X address depends
on the I/O configuration.
Since we are going to perform some math operations in BCD, this
instruction converts the data format from binary to BCD.
When X34 is on, channel 1 data is being sent to the CPU. The OUT
instruction moves the data from the accumulator to V3000.
LD
V3000
When X1 is on, channel 1 data is loaded into the accumulator.
MUL
K1000
Multiplies the accumulator contents by 1000 (to start the conversion).
DIV
K4095
Divides the accumulator contents by 4095.
OUT
V3100
Stores the converted result in V3100.
4–17
F4-04ADS 4-Channel Isolated Analog Input
Analog and
Digital Value
Conversions
Sometimes it is helpful to be able to quickly convert between the signal levels and
the digital values. This is especially useful during machine startup or
troubleshooting. The following table provides formulas to make this conversion
easier.
Range
If you know the digital value ...
$10V
A + 20D * 10
4095
D + 4095 (A ) 10)
20
$5V
A + 10D * 5
4095
D + 4095 (A ) 5)
10
0 to 5V
A + 5D
4095
D + 4095 (A)
5
0 to 10V
A + 10D
4095
D + 4095 (A)
10
1 to 5V
A + 4D ) 1
4095
D + 4095 (A * 1)
4
4 to 20mA
A + 16D ) 4
4095
D + 4095 (A * 4)
16
For example, if you are using the $10V
range and you have measured the
signal at 6V, you would use the following
formula to determine the digital value
that should be stored in the V-memory
location that contains the data.
If you know the signal level ...
D + 4095 (A ) 10)
20
D + 4095 (6V ) 10)
20
D + (204.75) (16)
F4–04ADS
4-Ch. Isolated Analog In.
D + 3276
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