Posted ByLeon on December 10, 2001 at 13:04:49:
In Reply to: remote modem linkup posted byHank Lothammer on December 09, 2001 at 20:28:56:
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