Modem Connection and Pinouts

The following figure shows you how to connect a controller to a modem.

 

Note

 The programming cable is a 4-wire cable. The cable is included with the Vision all-in-one kits.

 

Connecting a Controller to a Modem

General Information: Modem to Controller Interface (DCE to DTE)

The next figure shows the interface between the Data Communications Equipment (DCE; the modem) and the Data Terminal Equipment (DTE; the controller or PC).  The arrows show the direction of data flow. Note that:

 

 

Note

Unitronics controllers do not support all the control lines.

Modems should be initialized via the Modem Services> Prepare Modem procedure. This procedure:

  • Turns the DSR signal ON

  • Sets the appropriate PLC-modem communication parameters. These are:
    - 19200 bps, 8 bit, no parity, 1 stop bit

Connecting DSR and RTS signals causes the modem to be always ready to transmit\receive data.

Using Modem Kits

Unitronics' kits contain all of the elements you need to connect a controller to a modem using the appropriate PLC programming cable, as shown in the first figures at the beginning of this section.

Note that you must remove the PC adapter from the PLC programming cable and replace it with the modem adapter supplied in the kit.

In order to work with Unitronics controllers, you must initialize the modem via the procedure detailed in the Prepare PLC Modem topic.

The following list shows modem adapters supplied with the kits and their pin-outs. For updated information, consult your Unitronics distributor.

Standard Landline and Siemens GSM/GPRS modems

Sony Ericsson GM29 and Enfora GSM/GPRS modems

Wavecom GSM/GPRS modems

Note

Wavecom modem kits do not contain the PC to modem cable, MJ10-22-CS32, that is required for the Wavecom Prepare Modem procedure. This cable is available by separate order.

Using a Unitronics Adapter

If you are using a modem from an independent source, you can order one of the modem adapters described in the preceding section from Unitronics, and use this adapter to connect your modem to the PLC via the PLC programming cable.

Constructing Adapters

You can construct a D-type modem adapter yourself, using the appropriate pin-outs shown in the preceding section.

You can also construct a cable with 2 male D-type connectors, and then use it to connect a modem's serial port directly to the PC adapter on the PLC programming cable as shown in the next figure.

 

The tables below give the pin-outs of the programming cables, and show you an example of the pin connection you can use to construct a cable with 2 male D-type connectors to connect a PLC to a standard landline modem.

Vision 4-wire Programming Cable

PC -side

Adapter MJ10-22-CS25

 

PLC-side

Programming port

PC signals

D-Type 9 pin, female

RJ11

 

RJ11

Controller signals

 

DTR (out)

4

1

 

6

DSR (in) 

Unused

GND

5

2

 

5

GND 

 

TXD (out)

3

3

 

4

RXD (in) 

 

RXD (in)

2

4

 

3

TXD (out)

 

GND

5

5

 

2

GND

 

DSR (in)

6

6

 

1

DTR (out) 

Unused

Note

The 4-wire programming cable supplied with the controller connects RJ11 pins 2,3,4,5 to pins 5,4,3,2 respectively.

 

Example: D-type modem adapter cable to connect a Vision controller to a standard landline modem

Modem-side
(D-type 9-pin, male)

 

PLC-side

(D-type 9-pin, male)

DSR (out) +

RTS (in)

6+7

 

 

 

GND

5

 

5

GND

RXD (out) 

2

 

3

RXD (in)

TXD (in)

3

 

2

TXD (out)

GND

5

 

5

GND