VT manual
Section 1
Overview
The SIXNET VT-MODEMs are rugged industrial telephone modems that have been designed for operation in
electrical enclosures installed in harsh environments. All VT-MODEMs support all standard Hayes AT
commands, Fax Class 1 and Class 2 commands and S-registers and therefore can be set-up as an external
modem on any PC. The VT-MODEMs are compatible with any telecommunications or dial-up networking
software.
A VT-MODEM allows easy access to PLCs, SIXNET I/O and other devices via dial-in telephone connections.
The modem may be DIN rail or panel mounted for convenient and easy installation adjacent to other DIN rail
components inside of new or existing enclosures. Most Windows software can communicate through a VTMODEM to remote devices to perform file transfers, diagnostics, program debugging and many other operations.
All SIXNET Industrial Modems allow communication to remote sites for data retrieval or diagnostics.
Note: All VT-MODEM models communicate over analog phone lines only.
The SIXNET PLC Self-Dialing Modem (VT-MODEM-2) has all the features of the SIXNET Industrial Modem
(VT-MODEM-1), plus the ability to dial out based on an alarm contact or PLC discrete output.
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VT-MODEM -2 Self-Dialing Feature
The Self-Dialing Modem is triggered by a switch closure or PLC output signal. It dials a pre-stored phone
number and optionally identifies itself by way of a pre-stored ASCII message. Flexible features allow this modem
to perform retries or even connect to alternate number until it has verified that a connection has been established.
The call will terminate when either:
• The computer completes its polling and hangs up
• The modem discrete input is turned off
• A telephone line problem disrupts the call.
The VT-MODEM-2 enables field installed equipment to establish a telephone link based upon a simple switch
closure. This self-dialing modem adds “dial upon alarm” intelligence to any remote site. This enhanced modem is
ideal for:
DIALING UPON ALARM FROM ANY PLC
This modem establishes a connection based upon a coil output from any PLC. Once a connection has
been established, the PLC’s system (programming) port is connected to the computer at the other end of
the phone link and may be polled by that computer as if the computer had initiated the call. When the
modem connects to the central computer, it identifies itself so the computer can run the appropriate I/O
driver and interrogate the PLC.
SENDING A MESSAGE BASED UPON A SWITCH CONTACT
Locations that do not have PLCs (or other intelligence) can originate calls to alert you to low tank levels,
over temperature conditions, or other alarms. Simply connect the appropriate alarm contact to the
modem’s input. The modem will dial the pre-stored phone number and deliver the ID message to the
computer at the receiving end.
VT-MODEM -3 RS485 Port
The VT-MODEM-3 Industrial Modem Plus has a RS422 / RS485 port that can function in place of its RS232
port. The RS422 / RS485 port supports RS422 and RS485 full duplex, and two wire RS485 half duplex
communication to compatible devices. The VT-MODEM-3 is user-configurable to communicate through either
the RS232 port (VT-MODEM-1 mode) or through the RS422 / RS485 port. Only one port can be used at a
time.
VT-MODEM SETUP WIZARD
A modem setup utility is provided on the SIXNET CD to help you quickly configure any SIXNET Industrial
Modem. In most applications, no knowledge of modem AT commands or S register contents is necessary. Preconfigured profiles, for common situations are provided for your convenience. An extensive online help file is
provided with this utility.
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Section 2
Performance Specifications
Telephone Line (all models)
Max. Data Rate
Compatibility
Data Compression
Error Correction
Max Fax Modem Rate
Fax Modem Compatibility
Ringer Equivalent
Line Jack
Phone Jack (VT-MODEM-1 and –2)
33.6 kbps (V.34)
V.34, V.32bis, V.32, V.22bis, V.22A/B, V.23, V.21, Bell212A & 103
V.42bis/MNP 5
V.42/MNP 2-4
14.4 kbps (V.33)
Group 3 (V.33, V.17, V.29, V.27ter, V.21 ch. 2)
0.3
RJ11
RJ11
RS232 Port (all models)
Max. RS232 Rate
RS232 Signal Support
RS232 Connector
Command Set
115.2 kbps (Kilobaud)
TXD, RXD, CTS, RTS, DCD, DTR, DSR, RI, GND
DB9 female, RS232
All standard AT and S register commands including Class 1 and Class 2
Fax commands
RS422 / RS485 Port (VT-MODEM-3 only)
RS422 mode
RS485 modes
Signal rate
RS422 / RS485 distance
4 wire full duplex
2 or 4 wire party-line operation (half duplex)
Standard rates up to 115.2 kbps (Kilobaud)
Up to 0.5 miles
Status LEDs (all models)
CD
(Carrier detect)
TR (Data Terminal Ready)
RD (Receive Data)
TD (Transmit Data)
Power
The modem has detected a carrier on the phone line (a remote modem
has been detected).
The PC (or Gateway/VersaTRAK) has established a connection to the
modem and is ready.
Flashes as data is received from the phone line.
Flashes as data is sent out the phone line.
On when power is present.
General Characteristics (all models)
Input Power
Input Current
Certification
Operating Temperature
Storage Temperature
Humidity
Mounting
Dimensions
10 - 30 VDC (VT-MODEM-1, –2), 10 – 52 VDC (VT-MODEM-3)
65mA @ 24VDC (typical)
FCC Part 15 and FCC Part 68; UL 508; CSA C22.2/14;
ACA TS 001- 1997; ACA TS 002-1997; AS/NZS3260-1993;
AS/NZS3548-1995; CTR21 (98/482/EC); EN55022; IEC 950:1991.
-30 ° to 70 ° C
-40 ° to 85 ° C
5 to 95% RH (non-condensing)
DIN rail or panel mount
W x 4.75L x 1.35H inches
(8.2 W x 12.1 L x 3.4H cm)
PLC Discrete I/O Interface (VT-MODEM-2 only)
Trigger Input (From PLC)
Voltage Range
Input Current
Max. OFF Voltage
On-line Output (To PLC)
Output Characteristics
Max. Output Current
VT-Modem User Manual
Connects to PLC output. Starts auto-dialing upon transition from OFF to
ON. Modem will stay connected while input is ON.
9 to 30 VDC
6.5 mA at 24 VDC
5 VDC
Output is ON as long as a connection exists (carrier detect).
Sourcing – switches supply power
100 mA
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Section 3
VT-MODEM Mounting
The VT-MODEM snaps onto standard DIN rail (DIN EN 50022) or is mounted to a flat panel using #6 or #8
screws. See Figure 3-1. The modem can be installed in any orientation, directly adjacent to other DIN rail
components or in any convenient location within the enclosure. The modem should be installed within 6 feet of the
device it will be connected to. For SIXTRAK gateways and VersaTRAK RTUs, use the SIXNET RS232 cable
(VT-CABLE-MDM), which is 6 feet in length.
Figure 3-1: VT-MODEM DIMENSIONS, ALL MODELS
For DIN rail mounting, hook the top, rear of the modem onto the top edge of the DIN rail. Using a small flat head
screwdriver, pull down on the spring-loaded tab on the bottom of the modem and push the modem back against
the rail. Reverse these steps to remove the modem. See Figure 3-2 below.
Figure 3-2: DIN RAIL MOUNTING
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Section 4
Electrical Connections
RS232 Connections (All VT-MODEM Models):
Use a VT-CABLE-MDM or equivalent cable to connect the modem's RS232 port (DB9 Male cable end) to the
RS232 port on a SIXTRAK Gateway, VersaTRAK RTU or PC (DB9 Female cable end). As shown in Figure
4-1, the VT-CABLE-MDM is a straight through serial communications cable suitable for connecting a DTE
device (PC, Gateway or VersaTRAK) to a DCE device (VT-MODEM).
Cable requirements for PLCs and other devices may be different. Refer to the PLC or other device’s
documentation for cable pinouts. Some PLC cables are documented in the Technical notes provided on the
SIXNET Programmable I/O for Windows CD.
Figure 4-1: VT-CABLE-MDM Wiring
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VT-MODEM-1 Power, Phone Line Connections:
DC Power Wiring
Connect 10 - 30 VDC to the VT-MODEM-1 as shown in Figure 4-2. The modem can usually be powered
from the same DC source as other devices in the enclosure. All the screw terminals should be tightened to a
maximum of 3.48 in-lbs.
Telephone Cable
Connect analog phone lines to the RJ-11 jacks as appropriate. One RJ-11 jack is provided to connect directly to
a telephone (optional) and the second RJ-11 jack functions as the connection to the telephone network.
Figure 4-2: VT-MODEM -1 WIRING
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VT-MODEM-2 Power, Phone Line, Self-Dial Connections:
DC Power Wiring
Connect 10 - 30 VDC to the VT-MODEM-2 as shown in Figure 4-3. The modem can usually be powered
from the same source as other devices in the enclosure. All the screw terminals should be tightened to a maximum
of 3.48 in-lbs.
Telephone Cable
Connect analog phone lines to the RJ11 jacks as appropriate. One RJ-11 jack is provided to connect directly to
a telephone (optional) and the second RJ-11 jack functions as the connection to the telephone network.
PLC Self-Dial I/O Connections
Connect a 10-30VDC signal to the ‘From PLC’ (trigger input) terminal. An OFF to ON transition of this signal
starts the auto-dialing sequence. The modem will call and remain connected while the signal is ON. When the
signal goes false, the modem will terminate the connection or the call in progress.
The ‘To PLC’ (on-line output) terminal will go ON (ON = user supplied VDC input) when a modem to modem
connection has been established and the proper ‘Acknowledge Message’ has been received.
Figure 4-3: VT-MODEM -2 WIRING
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VT-MODEM-3 Power, Phone Line, RS422 / RS485 Connections:
DC Power Wiring
Connect 10 - 52 VDC to the VT-MODEM-3 as shown in Figure 4-4. The modem can usually be powered
from the same source as other devices in the enclosure. All the screw terminals should be tightened to a maximum
of 3.48 in-lbs.
Telephone Cable
Connect an analog phone line to the RJ-11 jack as appropriate.
RS422 / RS485 Cabling and DIP Switch Settings
Refer to Figure 4-4 for typical wiring configurations. Fabricate a cable to connect the modem's RS422 / RS485
port to the field device(s).
The VT-MODEM-3 has DIP switches. These switches establish the mode of operation for the RS422/RS485
port. Set these switches to match the type of wiring connected to the RS422/RS485 port. Refer to Figure 4-5 on
the next page. It is not necessary to cycle power to the modem if DIP switch changes are made.
Figure 4-4: Typical RS422 / RS485 Wiring
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Figure 4-5: Detailed RS422 / RS485 Wiring and DIP Switch Settings
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VT-MODEM -3 DIP Switch Summary
2 wire RS485 Cabling
Receive Bias Enabled (RS485 4 wire Cabling)
Transmit Bias Enabled (RS485 2 and 4 wire Cabling)
7 ON, 8 OFF = 2 wire Termination Enabled
7 ON, 8 ON = 4 wire Termination Enabled
7 ON, 8 OFF = 2 wire Termination Enabled
2 and 4 wire Termination Disabled
Transmit Bias Disabled (RS485 2 and 4 wire Cabling)
Receive Bias Disabled (RS485 4 wire Cabling)
RS422 or 4 wire RS485 Cabling
RS422 / RS485 Network Termination
The VT-MODEM-3 has built-in termination components for the Receive Data and Transmit Data signals.
Termination of these signals is enabled by setting DIP switches on the VT-MODEM-3. Termination components
are often built into other RS422 / RS485 devices, and are typically enabled by setting a jumper or DIP switch on
the appropriate device.
Here are some guidelines for the use of termination:
• Terminations should be enabled at both ends of an RS422 communication cable.
• Terminations should be enabled at both end stations on an RS485 network. No more than two stations
should be terminated on an RS485 network.
Bias Resistors (RS485 networks only)
On an RS485 two wire network there should be one pair of bias resistors acting upon the transmit/receive wires.
On an RS485 four wire network there should be two pairs of bias resistors; one pair on the receive wires and
one pair on the transmit wires. Bias resistors force the receive or transmit/receive wires to a known (non-floating)
state when none of the RS485 devices are transmitting data. If bias resistors are not present, some RS485
devices may experience communication errors due to noise on the floating wires. Bias resistors do not apply to
RS422 wiring because the wires are always driven by the two RS422 devices. The wires are not permitted to
float.
The location of the bias resistors is not critical. Typically they are installed at the master RS485 device. Bias
resistors are provided in the VT-MODEM-3 and are enabled through DIP switch settings. There should be only
one pair of these resistors connected to an RS485 two wire network, and only two pairs of these resistors
connected to an RS485 four wire network. Refer to Figure 4-5 for recommended VT-MODEM-3 DIP switch
settings. Do not enable the VT-MODEM-3 bias resistors if there are bias resistors enabled on one of the other
RS485 devices.
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Typical RS485 Network Bias and Termination
Configuring a PC Modem to Communicate with a VT-MODEM -3 in RS422 or RS485 Mode:
It may be necessary to change your PC’s modem settings when communicating with a VT-MODEM-3 running in
RS422 or RS485 mode. Here are the recommended settings:
1. The PC modem, VT-MODEM-3 and the modem to modem speed should all be set to the same rate.
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Section 5
Modem Configuration
Configuring a VT-MODEM for use with SIXNET I/O:
All VT-MODEM models are factory configured to use the default communication settings for SIXTRAK
Gateways and VersaTRAK RTUs. If a VT-MODEM is connected to a PLC, PC or other non-SIXNET device,
then it may be necessary to reconfigure the modem. See the upcoming sections for further details.
AT Command String at Powerup
Upon powerup, a SIXTRAK gateway or VersaTRAK RTU can send a command string to a VT-MODEM. This
capability can be used to assure that the modem is set to a particular mode of operation, such as auto answer
mode. Refer to the “Set Modem String” topic in the Plant Floor program’s online help for information on this
capability. Any standard AT command can be sent by the gateway or RTU.
Configuring a VT-MODEM as an External Modem on a PC:
The VT-MODEM can be connected directly to a PC. The modem will need to be “installed” in Windows prior
to use. Here are instructions to install the modem in both Windows 95, 98 and Windows NT.
Modem Installation in Windows 95/98
Plug and Play method (recommended):
1) With the PC off, connect DC power and the telephone line to the VT-MODEM. Connect a communications
cable (VT-CABLE-MDM or equivalent) between the VT-MODEM and the PC. Turn on the PC. During
the boot-up process, Windows should detect the modem and display the New Hardware Found dialog box.
2) Make the selection “Select from a list of alternative drivers”.
3) The Select Device dialog will be displayed. In the column labeled Manufacturers, select “Standard Modem
Types”. In the column labeled Models, select “Standard 28800 bps Modem”. Click OK. Windows will
then complete the boot-up process. (The standard Windows driver is used for the VT-Modem. Although
the VT-Modem supports baud rates to 33,600 bps, the selections in Windows are limited to 28800 bps.)
4) To verify that the modem has been installed, select Start à Settings à Control Panel, and then double click
the Modems icon. The modem should be listed as “Standard 28800 bps Modem”.
Here is an alternate modem installation procedure (use if the PC is already powered up):
1) Connect the DC power, communications cable (VT-CABLE-MDM or equivalent) and telephone line as
described above.
2) Select Start à Settings à Control Panel, and then double click the Modems icon.
3) The Install New Modem dialog box will appear. Do not select the “Don’t detect my modem, I will select it
from a list”. Instead, click Next and allow Windows to search the com ports and detect the modem.
4) Windows should find a modem called Standard Modem. Click Next and Windows will complete installation
of the Standard Modem. (Alternately, click Change and select “Standard Modem Types” from the
Manufacturers list, and “Standard 28800 bps Modem” from the Models list.)
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5) To verify that the modem has been installed, select Start à Settings à Control Panel, and then double click
the Modems icon. The modem should be listed as either a “Standard Modem” or a “Standard 28800 bps
Modem” depending on the steps followed above.
6) Upon re-booting the machine, Windows may still find the VT-MODEM as new hardware. If this happens,
select “Do not install a driver (Windows will not prompt again)”.
Modem Installation in Windows NT
1) Select Start à Settings à Control Panel, and then double click the Modems icon.
2) The Install New Modem dialog box will appear. Do not select the “Don’t detect my modem, I will select it
from a list”. Instead, click Next and allow Windows to search the com ports and detect the modem.
3) Windows should find a modem called Standard Modem. Click Next and Windows will complete installation
of the Standard Modem. (Alternately, click Change and select “Standard Modem Types” from the
Manufacturers list, and “Standard 28800 bps Modem” from the Models list.)
4) To verify that the modem has been installed, select Start à Settings à Control Panel, and then double click
the Modems icon. The modem should be listed as either a “Standard Modem” or a “Standard 28800 bps
Modem” depending on the steps followed above.
Once the VT-MODEM modem has been added to your Windows 95, 98 or NT system, it is ready for use.
If you are using SIXNET I/O, you can use the SIXNET Sixdial software to dial out and establish a connection
with your SIXNET I/O. The Sixdial utility allows other SIXNET programs to perform operations such as data
transfers, hardware configuration and diagnostics, and ISaGRAF programming. (Refer to the on-line help in the
Sixdial utility for more information on these software tools).
If you are using a PLC or other device, refer to the documentation for that device as necessary.
To Remove a Modem
If it ever becomes necessary to re-install the modem for any reason, select Start à Settings à Control Panel,
and then double click the System icon. Next, click the Device Manager tab. The list should display a Modems
icon. Double click the Modems icon. Highlight the modem to be removed and then click the Remove button. To
reinstall the modem, follow the installation steps as previously described.
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Configuring a VT-MODEM Using the VT-MODEM Setup Wizard:
It is highly recommended that the SIXNET VT-MODEM Setup Wizard be used for VT-MODEM configuration.
Simply check the appropriate boxes, choose the appropriate communication settings from the dropdown lists,
and load the configuration into the VT-MODEM. This utility does not require user knowledge of AT commands
and S-registers.
Refer to the online help system in the VT-MODEM Setup Wizard for instructions and application notes.
Note:
The VT-MODEM Setup Wizard must be used to configure the self dial parameters of the VT-MODEM-2 and
the RS422 / RS485 port parameters of the VT-MODEM-3.
Setting the Modem's Baud Rate for the PLC
The VT-MODEM has an automatic baud rate detection feature that lets the modem recognize commands through
its serial port at any supported baud rate. However, if the modem is connected to a device that does not send
commands or data unless spoken to (such as most PLCs), then the modem will pass information from the phone line
to its serial port at the last auto-detected baud rate. This is typically the baud rate used by the VT-MODEM setup
Wizard when configuring the modem.
The VT-MODEM is defaulted at the factory for 9600-baud. To change this setting, connect the modem to a PC.
Start the VT-MODEM setup Wizard and choose the baud rate that matches the PLC’s baud rate. Then choose the
appropriate settings and write the configuration to the modem. Exit the VT-MODEM setup Wizard and reconnect
the modem to the PLC. (Be sure to cycle power to the modem.) Call the modem and verify that the PLC is
responding to commands.
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Limiting the Phone Line Connection Speed for Reliability
Typically, when a modem to modem connection is established, the two modems negotiate and connect at the fastest
possible phone line speed that is within the capability of both modems. The quality of the phone line connection
(during the negotiation) will be taken into account. If both modems are of a modern design (such as the VTMODEM), the phone line speed can be 33.6K bits per second (or higher, using data compression). Note that this
phone line speed is independent of the DTE (serial port) speed, though some older modems require that the phone
line speed and DTE speed be the same.
In practice the quality of any phone line changes continually, and frequent data errors may occur. The probability of
errors usually increases as the phone line speed increases. Therefore, it is often desirable to restrict the phone line
speed to a rate that will provide good performance and yield reliable data. It is also commonplace to restrict the
phone line speed to maintain compatibility when replacing an older modem with the VT-MODEM.
By default, the VT-MODEM will permit any phone line speed up to 115.2 kbps when data compression is enabled.
If you experience intermittent or unreliable communication, try setting the modem to modem speed (in the VT
MODEM Setup Wizard) to a lower value, to restrict the phone line speed. (Remember to load the new
configuration to the modem.)
VT-MODEM Profile Summary
Here is a summary of the active configuration, user profile 0, user profile 1 and the factory defaults when the
modem is shipped.
Each time the modem is powered up, first the factory default settings (as listed in Section 6) are loaded into the
active configuration. Next, the designated user stored profile is loaded into the active configuration. User profile 0
is loaded by default (see the &Y command in Section 6) and it contains all factory defaults with the exception that
it is set to auto answer (register S0=1), and ignore DTR (&D0).
The User profile 1 contains all normal factory defaults (as listed in Section 6).
ACTIVE CONFIGURATION:
B1 E1 L1 M1 N1 Q0 T V1 W0 X4 Y0 &C1 &D0 &G0 &J0 &K3 &Q5 &R1 &S0 &T5 &X0 &Y0
S00:001 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:050 S08:002 S09:006
S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007 S37:000 S38:020 S44:020
S46:138 S48:007 S95:000
STORED PROFILE 0:
B1 E1 L1 M1 N1 Q0 T V1 W0 X4 Y0 &C1 &D0 &G0 &J0 &K3 &Q5 &R1 &S0 &T5 &X0
S00:001 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014 S11:095 S12:050 S18:000
S36:007 S37:000 S40:104 S41:195 S46:138 S95:000
STORED PROFILE 1:
B1 E1 L1 M1 N1 Q0 T V1 W0 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q5 &R1 &S0 &T5 &X0
S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014 S11:095 S12:050 S18:000
S36:007 S37:000 S40:104 S41:195 S46:138 S95:000
FACTORY DEFAULTS:
B1 E1 L1 M1 N1 Q0 T V1 W0 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q5 &R1 &S0 &T5 &X0
S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014 S11:095 S12:050 S18:000
S36:007 S37:000 S40:104 S41:195 S46:138 S95:000
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Section 6
AT Command Summary
All VT-MODEM models support the AT commands, Fax Class 1 and Class 2 commands listed in this Section.
The VT-MODEM contains a set of factory default settings, which can always be restored by the user. (See the
&F command.) The modem also provides two user profiles (profile 0 and profile 1) which hold settings as set
and saved by the user. (See the &W command.) The settings currently in use by the modem are generally
referred to as the active configuration.
Notes:
VT-MODEM-2 self-dial parameters and VT-MODEM-3 RS422 / RS485 port parameters can only be set using
the VT-MODEM SETUP Wizard, which is provided on the SIXNET Programmable I/O for Windows CD.
Refer to the on-line help in the VT-MODEM Setup Wizard for more information.
The following tables only list the supported AT commands. The valid parameters and default settings for each AT
command are documented in the online help system of the VT-MODEM Setup Wizard.
Command
A/
A
AT=x
AT?
Bn
Cn
Dn
E
Fn
Hn
In
Ln
Mn
Nn
On
P
Qn
Sn
Sn-x
Sn?
T
Vn
Function
Re-execute Last Command; do not precede by AT command and do not follow with a
carriage return.
Go off hook and Answer A Call
Write value x to last selected register.
Report the value of last selected register.
Set data standard to CCITT(Europe et. al.) or Bell Mode(U.S., Canada) for
connections at 300 or 1200 bps.
Carrier Control (parameter = 1 only)
Dial (originate a call); typical usage: ATDT5551212 to tone dial number. ATDS=n to
dial nth stored number.
Echo command to monitor when typed
Not available.
Disconnect (Hang up)
Identification; reports product code, name, ROM and firmware data, etc.
Speaker Volume (not available)
Speaker Control (not available)
Automode Enable; enabled allows connection at highest possible modem speed,
disabled fixes speed according to register S37.
Return To On-line Data Mode
Set Pulse Dial Default.
Quiet Results Codes Control; when enabled, result codes are reported to the monitor.
Establishes S Register n as the last register accessed
Write value x to S Register n.
Reports the value of S Register n.
Set Tone Dial Default
Set Result Code Format to terse or verbose.
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Wn
Xn
Yn
Zn
&Cn
&Dn
&Fn
&Gn
&Jn
&Kn
&Mn
&Pn
&Qn
&Rn
&Sn
&Tn
&V
&V1
&Wn
&Xn
&Yn
&Zn=x
%E
%L
%Q
%7
%8
\Kn
\Nn
\Vn
+MS
+Hn
-SDR
**
%Cn
\An
\Bn
)Mn
*Hn
Connect Message Control sets the format of the connect messages.
Extended results code
Long space disconnect
Perform Soft Reset and Restore stored user configuration profile 0 or 1.
RLSD (DCD) Option; set DCD signal to indicate presence of carrier or forces DCD
signal on at all times.
DTR Option; set how modem interprets the DTR signal.
Restore factory configuration profile 0 or 1.
Select guard tone
Telephone jack control
Set Flow Control
Asynchronous/synchronous mode selection
Select pulse dial make/break ratio
Asynchronous/synchronous mode selection
RTS/CTS option sets how the modem controls the CTS signal
DSR Override sets how the modem controls the DSR signal
Test & diagnostic settings
Display current configuration, stored user profiles and stored telephone numbers
Display last connection statistics
Store current active configuration in one of the two user profiles
Select synchronous clock source
Designate a default-reset profile. This profile will be active after a hard reset
Store phone number; n = 0 to 3 and x = dial string
Enable/disable line quality monitor and autoretrain or fallback/fail forward
Report line signal level
Report line signal quality
Plug and Play Serial Number
Plug & Play Vendor ID, Prod. No.
Break Control sets how the modem responds to a break signal
Sets the Operating Mode of the modem: direct, normal, reliable or auto reliable
Single Line Connect Message Enable
Select Modulation allows control of the modulation the modem uses to negotiate a
connection
Enable/Disable RPI and DTE Speed
Enable/disable distinctive ring
Download to flash memory
Enable/Disable Data Compression (MNP5, V42bis or both)
Select Max MNP Block Size
Transmit Break to Remote sets the length of break signal sent to remote modem(in non
error correction mode)
Enable Cellular Power Level Adjust (only included for compatibility and performs no
function)
Link Negotiation Speed (only included for compatibility and performs no function)
VT-Modem User Manual
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Last Revision: 07/18/01
-Kn
-Qn
-SEC=n
@Mn
:E
*B
*D
*NCn
FAX CLASS 1:
+FCLASS=n
+FAE=n
+FRH=n
+FRM=n
+FRS=n
+FTH=n
+FTM=n
+FTS=n
FAX CLASS 2:
+FCLASS=n
+FAA=n
+FAXERR
+FBOR
+FBUF?
+FCFR
+FCON
+FCIG
+FCIG:
+FCR
+FCSI:
+FDCC=
+FDCS:
+FDCS=
+FDIS:
+FDIS=
+FDR
+FDT=
+FDTC:
+FET:
+FET=n
+FHNG
MNP Extended Services
Enable Fallback to V.22bis/V.22 (only included for compatibility and performs no
function)
Enable/Disable MNP10-EC
Initial Cellular Power Level Setting (only included for compatibility and performs no
function)
Compromise Equalizer Enable (only included for compatibility and performs no
function)
Display Blacklisted Numbers
Display Delayed Numbers
Country Select
Service Class
Data/Fax Auto Answer
Receive Data with HDLC Framing
Receive Data
Receive Silence
Transmit Data with HDLC Framing
Transmit Data
Stop Transmission and Wait
Service Class
Adaptive Answer
Fax Error Value
Phase C Data Bit Order
Buffer Size (Read Only)
Indicate Confirmation to Receive
Facsimile Connection Response
Set the Polled Station Identification
Report the Polled Station Identification
Capability to Receive
Report the Called Station ID
DCE Capabilities Parameters
Report Current Session
Current Session Results
Report Remote Capabilities
Current Session Parameters
Begin or Continue Phase C Receive Data
Data Transmission
Report the Polled Station Capabilities
Post Page Message Response
Transmit Page Punctuation
Call Termination with Status
VT-Modem User Manual
Page 19
Last Revision: 07/18/01
+FK
+FLID=
+FLPL
+FMDL?
+FMFR?
+FPHCTO
+FPOLL
+FPTS:
+FREV?
+FSPL
+FTSI:
Caller ID:
#CID=0
#CID=1
#CID=2
AudioSpan and
DSVD:
-SMS=
-SSE=
-SQS=
Synchronous
Access Mode:
+ES
+ESA
+ITF
Session Termination
Local ID String
Indicate a Document for Polling
Identify Model
Identify Manufacturer
Phase C Time Out
Indicates Polling Request
Page Transfer Status
Identify Revision
Enable Polling
Report the Transmit Station ID
Disable Caller ID
Enable Caller ID with Formatted Presentation
Enable Caller ID with Unformatted Presentation
Select AudioSpan/DSVD Mode
Enable/Disable DSVD
Select AudioSpan Modulation
Enable/Disable Synchronous Access Mode in the client or central site modem
Configures the Operation of the Synchronous Access Submode
Selects Transmit Flow Control Thresholds
VT-Modem User Manual
Page 20
Last Revision: 07/18/01
Section 7
S Register Summary
Note:
The following tables only summarize the supported S-registers. A description for each S-register may be found in
the online help system of the VT-MODEM Setup Wizard.
Register
Function
Range
Units
Default
S0
S1
S2
S3
S4
S5
S6
Number of rings required before modem auto answers
Ring counter increments each time a ring is detected
Escape character
Carriage return character
Line feed character
Backspace character
Maximum time to wait after going off-hook to dial when
blind dialing
Maximum time to wait for carrier after dialing before
hanging up
Pause time for dial delay modifier
Carrier detect response time; duration that carrier must be
present for modem to consider it a valid connection
Carrier loss disconnect time; carrier must be absent for this
time for modem to consider it a lost connection
DTMF tone duration
Escape prompt delay; this delay must be present after
receipt of the last character of the escape sequence(
before receipt of any other character) for the escape
sequence to be recognized
Reserved
General bit mapped options indicates the status of the
following options: echo, quiet mode, results codes,
tone/pulse and originate/answer
Reserved
Test mode bit mapped options (&T)
Reserved
Test timer –length of test initiated by &Tn command
AutoSync Bit Mapped Options
AutoSync HDLC Addr or BSC Sync Char
V24/general bit mapped options indicates the status of the
following options: CTS(&Rn), DTR(&Dn), DCD(&Cn),
DSR(&Sn), long space disconnect(Yn)
Speaker/results bit mapped options indicates the status of
the following options: speaker control(Ln), volume(Mn),
results codes(Xn)
General Bit Mapped Options
Sleep inactivity timer sets the length of time that the
modem will operate in normal mode without activity on the
0-255
0-255
0-255
0-127
0-127
0-255
2-255
rings
rings
ASCII
ASCII
ASCII
ASCII
sec
0
0
43
13
10
8
2
1-255
sec
50
0-255
1-255
sec
0.1s
2
6
1-255
0.1s
14
50-255
0-255
0.001s
0.02s
95
50
-
-
138(8Ah)
0-255
0-255
-
s
-
0
0
0
0
52(34h)
-
-
117(75h)
0-255
s
58(3Ah)
0
S7
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
VT-Modem User Manual
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Last Revision: 07/18/01
S25
S26
S27
S28
S29
S30
S31
S32
S33
S34-S35
S36
S37
S38
S39
S40
S41
S42-S45
S46
S48
S82
S86
S91
S92
S95
phone or RS232 port before entering sleep mode
Delay to DTR (CT108) off sets time modem ignores DTR
signal before taking action specified by &Dn
RTS-to-CTS (CT105 to CT106) delay if &R0 is set
General Bit Mapped Options for sync/async
control(&Mn/&Qn), leased line control(&Ln), clock
select(&Xn), Bell/CCITT mode(Bn)
General Bit Mapped Options indicates options for pulse
dialing(&Pn), MNP Link negotiation speed(*Hn)
Flash Modifier Time sets the length of time the modem will
go on hook if the flash dial modifier(!) is encountered in the
dial string
Inactivity timer sets the length of time the modem will
remain on line if no data is sent or received
General Bit Mapped Options
XON character
XOFF character
Reserved
LAPM Failure Control used when register S48=128
Desired Line Connection Speed (when N1 is set)
Delay before forced hang-up (time delay between the
receipt of H command to disconnect and the actual
disconnect operation
Flow control bit mapped options
General bit mapped options
General bit mapped options
Reserved
Enable/Disable Data Compression
V.42 Negotiation Control
LAPM Break Control
Call Failure Reason Code; when the No Carrier result code
is issued, the reason for the failure is written to this register
PSTN transmit attenuation level
Fax transmit attenuation level
Result code messages control
VT-Modem User Manual
Page 22
0-255
s/0.01s
5
0-255
-
0.01s
-
1
73(49h)
-
-
0
0-255
10 ms
70
0-255
10s
0
0-255
0-255
0-255
ASCII
ASCII
s
194(C2h)
17(11h)
19(13h)
7
0
20
0-255
-
3
104(68h)
195(C3h)
138
7
128(40h)
-
0-15
0-15
-
dBm
dBm
-
10
10
0
Last Revision: 07/18/01
Section 8
Maintenance Information
Troubleshooting Tips
VT-MODEM Default LED Indications
All VT-MODEM models have the following LEDs.
LED
Default Indication
Carrier Detect
This LED will come ON once a phone line connection has been established, and
will remain on for as long as the connection is maintained.
Data Terminal Ready
This LED should be ON at all times.
Receive Data
This LED will come ON whenever characters are received through the phone line.
Transmit Data
This LED will come ON whenever the modem sends characters out the phone line.
Power LED
Normal Indication (All models): This LED will be ON when power is applied to the
modem.
Additional States (VT-MODEM-2 only): A “Slow” blink indicates an invalid
configuration or that the “Block COM Port Until Connected” feature is enabled. A
“Fast” blink indicates that a self-dial is in process or that the modem is in
“Configure Self-dialing Parameters’ mode.
Note: The RD and TD LEDs indicate the flow of characters in and out of the phone line interface of the VTMODEM, and are not directly connected to the RS232 port (all models) or RS422 / RS485 port (VTMODEM-3).
Reconnecting Serial Cables
It is important to cycle (remove and then reapply) DC power to a VT-MODEM each time the RS232 or RS422 /
RS485 cable is disconnected and then reconnected. The serial port of the modem may not function properly if power
is not cycled.
Resetting the VT-MODEM (all models)
If it ever becomes necessary to completely reset the modem including both user profiles to the basic factory default
settings , the following command can be issued:
AT&F&W&W1 [CR]
This command string will load the factory defaults into the active configuration (&F) and then save those settings
into both user profile 0 (&W) and user profile 1 (&W1).
Note that after the modem is reset completely to the factory defaults, it will no longer be set to auto-answer, which
is often necessary for the modem to work when connected to a remote device. Use the VT-MODEM Setup Wizard
to adjust these settings appropriately.
VT-Modem User Manual
Page 23
Last Revision: 07/18/01
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