I have a problem of communicate the Twido PLC by using an US Robotic 56K Fax modem, then communication port in the PLC i select port 1 and the communication protocol that i use is the modbus with the configuration of Baudrate is 19200, parity is none, Data Bits is 8 bit RTU, stop bit none, response time out is 1000ms, and interframe delay is 60ms. any one have the experience in doing this kind of project or using a GSM modem .... please help me.... urgent...

 

As I know, you can not connect Twido to any modem. Pls check again with the Twido catalogue, what kind of modem you should use.

 

Automated Solutions' Modbus RTU/ASCII ActiveX control supports Modem operation. You can download a fully functioning evaluation version at http://www.automatedsolutions.com. There is a pre-built HMI application that will have you communicating in seconds.

You might need to consider using Modbus RTU with no parity or Modbus ASCII due to modem limitations.

 

More info would be good... Like software used, hardware used etc...

So basically you have a PC, with an internal modem, trying to connect directly to a Twido serial port?

At first sight, I would say it'll never work. Different protocol (depending on modem model RS-232, RS-485).

Option 1: Connect directly through the serial port of your PC to the Twido with same serial configurations for distances of up to 50 feet null modem cable, or for greater distances, connect the serial port of the PC to 1 modem, then RS485 or TCPIP to second modem then back to RS232 on the Twido.

Option 2: Depending on modem model, RS485 directly to Twido port set for RS485 (MB+)

Option 3: Use RS232/RS485 converter from serial port of PC, then access PLC port as Modbus+

There are other options available as well

Have fun & good luck...