Hi,

I have a westermo gdw 11 gsm modem connected to a micrologix 1000 and i am trying to communicate to the plc from a remote location. I have configured a df1 driver through a modem and i have df1 driver running properly and connected to the westermo modem but when i look RSwho i cannot see the plc. Can any one give me pointers. I have a yellow question mark appearing in rswho at times.

One simple troubleshooting step would be to hook up your computer directly to the MicroLogix 1000 and see if RSLinx browses it correctly (the MicroLogix 1000 icon appears as Node 1) when connected directly.

A yellow question mark indicates that a device has replied to browse queries but not to identity requests. This means that either you don't have the right EDS file installed (very unlikely unless your RSLinx version is a decade old) or that the device is only replying to a small number of query packets from RSLinx.

Does Westermo make any representations about supporting DF1 Full Duplex, or any other full duplex protocol ?

I have had very poor results with GSM modems because they take a long time to connect and send even small packets, which any DF1 protocol relies on for acknowledgement. A serial data analyzer might be necessary to troubleshoot this problem.

You might also want to try changing the Advanced Browse Settings in RSLinx, to extend the timeout for the DF1 driver from the default 3 seconds out to 5 or 10 seconds.

Ken has the correct first steps when he says verify local commincation first. Also what DF-1 speed are you trying to use. I had a modem {not your brand} unit in FL talking across phone lines that was great at 19.2 when dialed from within the same city, but my home office in KY had no success until we changed the speed to 9600.
Also it might be possible that your PC is connecting to the modem at a speed higher then the DF-1 setting. IE your PC connects to teh mdoem at 33.6 but the DF-1 is set to 19.2 or 9600. There is a knowledgebase articel I recall seeing on AB's sitte about forcing your PC modem to dial at the anticipated DF-1 speed. A little search might prove fruitful if this is happening to you.