Re: remote modem linkup

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Comments:: Thanks Leon for your email reply. I'm posting my followup for the benefit of anyone who runs into the same problem. : << Yes, I was able to use an extra fax line to do my testing. I'm quite aware of the modem settings as well. >> : << Yes, and I've been in touch with my distributor PC-IO.com today >> : << Today with the aid of the distributor who sold me both T100's I think the problem may be narrowed down to the remote modem. He connected to my remote modem then tried to monitor it. He was unsuccessful. I then connected to his remote modem, which is plugged into his PLC and I was able to monitor I/O, force I/O... what one would expect. So I think the problem lies in my modem. I admit it was a swap shop modem and who knows; maybe there was a potential problem from the start. Perhaps you can help me with this symptom, shouldn't the external modem echo back commands if it's set to do so? When I connect the modem to my PC com1 port, using Hyperterminal to test it, I can send AT commands and it responds, but it won't echo back. It seems to me that the echo would return on the transmit line, am I correct? If so, then no echo may mean no returning signals of any kind and maybe that's why the modem won't talk to the T100. I'm prepared to just go out and buy a new USR external modem, but I'd like to make sure. >> : << The Internet version of Trilogi may not be the best solution for my customer. I think the modem linkup will be best because they won't have a PC near every machine. At least not right now. >> : : You mentioned that the modem connection works for a while and now it refuses, was that initial success within your own facility where you are able to set the remote modem to the required settings of 9600,8,n,1, no flow control and no error correction protocol? I assume that if you had succesfully gotten the modem to work you have already know all the requirement for modem communications. Did you refer to the document in the MODEM.ZIP file? : : Do you have someone in the remote end who is knowedgeable with the PLC to modem requirement to help you with the setup? Remember that the modem needs to be setup to run in auto-answer mode and put itself at the correct baud rate and protocol settings. If you have manually changed the modem setting using HyperTerminal (I am refering to the modem at the remote end) you will need to execute a specific AT command to save that setting into non-volatile memory. Otherwise after the modem is powered down the setting will be gone unless the PLC is programmed to set the modem when both are powered up. : : Using the Internet TRiLOGI should be technically less complex than handling modem communication directly. If your remote location has a PC that can go on-line and has a public IP address, then you just need to run the TLServer at the remote PC and you can then perform complete programming and on-line monitoring as if you are right there at the workstation with the PLC. In fact multiple clients (ladder program and monitoring) can access the same TLServer simultaneously, so that personnel of both ends can be monitoring the same PLC at the same time. : : : I'm having a very difficult time accessing the T100MD via a simple modem. I've had it working for a while and then it spontaneously refuses. I'm using a 14.4 external USRobotics modem and my Dell laptop. I've tried every possible init string, every port wiring combination possible. The modem is functional since I can command it with hyperterminal. Both com1 & com3 ports on the PLC are functional (I use an RS485/RS232 adapter for com3). The problem seems to be between the external modem and the PLC at the remote end. The finished unit I developed is overseas now and I have to be able to access it for program revisions and custom tayloring. This should be a no brainer, but I'm under pressure now and running out of ideas. I tried other PC's but still no luck. Should I use two matching external modems? Should I consider the Trilogi Windows Internet program version? : : : Any insight, ideas, solutions, even some cheese with my wine would help. : : : Hank

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