About Modems

You can use the controller with either a PSTN modem or a cellular modem. When you use a cellular GSM modem, you can also program the controller to both send and receive SMS messages from a GSM cellular phone.

Before you can use modems in your application, you must use Modem Services to initialize both PC and PLC-side modems.

Modem services

Modem Services is located on the Connections menu.

To use Modem Services, connect the modem to a PC, using the cable supplied by the modem manufacturer. You can then initialize the modem.  

Once you have connected initialized modems to your PC and PLC, you can use Modem Services to establish communications with a remote PLC and perform tasks, just as you would if the PLC were directly connected to your PC. For example, you can:

Modem Tips

To avoid compatibility problems, use modems produced by the same manufacturer and of the same model. This is due to lack of standardization between modem manufacturers, which may result in communication conflicts.

Note ♦

The PC-modem cable is not the same type of cable used to connect between the controller and the modem. Ensure that the cable used to connect the PC to the modem provides connection points for all of the modem's pins.

♦

Jazz Controllers

  • Jazz controllers do not comprise an integral serial port. A Jazz controller cannot be connected to a modem unless it has been installed with an appropriate add-on port module.

  • Serial communications capabilities are determined by the type of Add-on Module.

  • Default COM settings and pin-outs are given in the technical specifications of the relevant Add-on Port.

  • The MJ20-PRG Programming Port may be used for RS232 communications with devices that supply active (RS232 positive voltage) DTR and RTS signals, such as most modems. Note that modems require an appropriate adapter.

♦

If calls are routed via a switchboard, note that the switchboard settings may interfere with communications. Consult with your switchboard provider

♦

If, within the modem initialization strings, the parameter S7 is too short to permit the PLC's modem to answer, an error will result.
For example, if this parameter is set as S7=30, the PC modem will wait for 3 seconds to receive an answer from the PLC's modem. If the PLC modem does not answer before the 3 seconds have elapsed, the S7=30 parameter is exceeded, and the PC modem will return the No Carrier error.

♦

PC/PLC modem communications: Both PC and controller must use the same type of modem: either landline or, GSM.

♦

Known compatibility issue: Sony Ericsson Modems.

Unitronics products are compatible with the following Sony Ericsson Modems:

  • - Model GT47 R5xxxx and higher

  •  - Model GM29 R6xxxx and higher

This means, for example, that Unitronics cannot guarantee compatibility with a Sony Ericsson Modem model GM29 R4xxxx.

 

Related Topics
PC-Side Modems
PLC-side Modems

For advanced users, check: How the PLC works with a modem.