Technical Note #639

VT-MODEM interfaces with Telemecanique TSX Micro PLC

Abstract: This Technical Note explains the procedure to remotely access a Telemecanique Modicon
TSX Micro CPU 3722 PLC through SIXNET Industrial Modems.

Using the dialing utility in the Schneider Automation PL7 PRO software, the TSX Micro
PLC can be remotely accessed via telephone wiring using a pair of SIXNET Industrial
Modems.

Software Used:

· Schneider Automation PL7 PRO v4.0

· SIXNET VT-MODEM Setup Wizard v1.15

Hardware Used:

· (1) Telemecanique Modicon TSX Micro CPU 3722 PLC

· (1) TSXPSX1130 Cable (PLC to modem connection)
· (1) TSXPCU1131 Cable (PC to PLC connection)
· (1) SIXNET VT-MODEM-1
· (1) SIXNET VT-MODEM-2
· (1) VT-CABLE-MDM (straight-thru male-to-female DB9 serial cable for PC to modem connection)
· (2) RJ-11 Phone cables

PC and VT-MODEM-1 Windows Setup:

Note: A SIXNET VT-MODEM-1 was used during testing on the local PC running PL7 PRO software.
However, most internal PC modem cards will function properly as the dialing modem in this
application.

To configure Windows to recognize the VT-MODEM-1, go to Start à Settings à Control Panel à

Phone and Modem options. Next, go to the Modems tab in the Phone and Modem options window, and
then click on Add… Next, check the “Don’t detect my modem; I will select it from list” box and
manually select “Standard 28800 bps Modem” from the modem type list. Refer to screen shots 1 and 2
for details of how the modems were configured.
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 Screen Shot 1 Screen Shot 2

Configuring the Hardware:

· TSX Micro PLC: Connect the TSX Micro PLC to a PC running PL7 PRO software via the
TSXPCU1131 cable to the PC’s Communication port and the TSX Micro’s TER port. Open the
hardware configuration screen for the TSX Micro’s Channel 0. Configure the Baud Rate, Data
bits, Parity and Stop bits for 9600, 8, None, 1 respectively. Set the Wait time for 250 ms (See
Screen Shot 3). Go to PLCàConnect to transfer the file from the PC to the PLC. Successful
communication will be indicated when the ‘ONLINE’ message is displayed on the bottom of the
main PL7 screen.

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 Screen Shot 3

· VT-MODEM-1: Connect the VT-MODEM-1 directly to a PC’s COM port via the VT-
CABLE-MDM supplied with the modem. Open the VT-MODEM Wizard. In the ‘Read
Configuration’ window select ‘VT-MODEM-1 (Industrial Modem)’ and click on ‘Next’. The
‘COM Parameters’ Window must match the configuration used in the TSX Micro PLC, so set the
Flow Control to None, Baud rate, Data bits, Parity, Stop bits should be set to 9600, 8, None, 1
respectively (See Screen Shot 4).
Note: The pre-configured VT-MODEM Wizard configuration file, TSXMicro_MDM2.6ms, is
available on the latest SIXNET CD or the SIXNET industrial modem website
www.industrialmodem.com.

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 Screen Shot 4

Next, in the ‘Modem Parameters’ window put Flow Control to None, check the ‘Disable Error
Correction’ check box and leave the rest of the options at their default values (See Screen Shot
5). Finally, load the configuration to the modem by selecting the ‘Write Configuration to the
Modem’ button in the ‘Write Configuration’ window.

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 Screen Shot 5

· VT-MODEM-2: Configure the VT-MODEM-2 the same as the VT-MODEM-1, except in

the ‘Self-Dialing Parameters’ window you should check the ‘Block COM Port Until Connected’
check box (See Screen Shot 6).

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 Screen Shot 6

Connecting the Hardware:

· Connecting the modems to the devices: Connect the VT-MODEM-1 to a PC’s COM port
via the VT-CABLE-MDM cable that came with the modem. The VT-MODEM-2 connects to the
TSX Micro PLC’s TER port via the TSXPCX1130 cable.

· Connecting the phone lines: The two modems were connected to an internal analog phone
system through their Line RJ11 jacks using standard RJ11 telephone cables.

Establishing the Connection:

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 · Dial Utility in PL7 PRO: To use the dialing utility within the PL7 PRO software, go to
PLCàDefine PLC Address…àOptionsàConfiguration of the DriversàUNITELWAY
DriveràConfigurationàEdit… In the Uni-telway tab check the ‘Use Modem’ Check box, add
‘ATDT’ to the Hayes text box and the Phone Number of the answering modem in the ‘Phone
Number’ text box (See Screen Shot 7). Set the parameters in the ‘Line Parameters’ tab to match
the communication parameters in the PLC’s Hardware Configuration (See Screen Shot 8). The
settings in the ‘Advanced’ tab should be set to defaults (See Screen Shot 9).

Screen Shot 7 Screen Shot 8

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 Screen Shot 9

‘OK’ out of the ‘Station Parameters’ window and the ‘UNITELWAY Configuration’ window to reset
the driver. In the Main PL7 PRO window go to PLCàConnect to establish the modem-to-modem
connection and go online with the PLC. Once the CD LED on the modems turn on solid, the TD and RD
LED’s should blink rapidly, indicating there is successful communication. To Hang-up the connection,
cycle power to the VT-MODEM-1 or close PL7 PRO and follow the directions to terminate the
connection in the ‘Windows HyperTerminal’ section below.

· Windows HyperTerminal: To establish a modem-to-modem connection using Windows

HyperTerminal, configure the UNITELWAY Driver in the PL7 PRO software exactly the same
as defined in the section above except do not check the ‘Use Modem’ check box in the ‘Uni-
telway’ tab. Open Windows HyperTerminal to create a new session and give the connection a
meaningful name (in this case TSX Micro was used). In the ‘Connected To’ field, select the
communication port the VT-MODEM-1 is connected to on the PC. In this case, COM 1 was used
(See Screen Shot 10). In the ‘Properties’ window the port parameters should be set to match the
port parameters of PLC 9600 Baud, 8 Data bits, None Parity, 1 Stop bit, None Flow Control (See
Screen Shot 11). When in the main HyperTerminal, window type AT <enter> to verify a

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 successful connection between the VT-MODEM-1 and the PC. An OK should result if the
connection is valid. Now dial the phone number associated with the VT-MODEM-2 by typing
ATDT# <enter>, where # is the phone number. The modem-to-modem connection is indicated by
the ‘CONNECT 9600’ message (See Screen Shot 12). Now that the link between the PC and
TSX Micro PLC is established, close out of HyperTerminal and Open PL7 PRO software. Now
access the PLC by selecting PLCàConnect. The TD and RD LED’s should blink rapidly,
indicating valid communication.

Screen Shot 10 Screen Shot 11

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 Screen Shot 12

To terminate the modem-to-modem connection, close PL7 PRO and open the HyperTerminal session
created previously. Type +++ and wait for the OK message from the modem. Then type ATH to hang-up
the connection (See Screen Shot 13).

Screen Shot 13

Conclusion: This test successfully established communications between a PC and TSX Micro
PLC via SIXNET Industrial Modems.

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