Modem to modem using SLC 5/04

[rta53]

We have a customer where we already have an Allen Bradley modem kit installed. We have a PC set up here at our place with a US Robotics modem that periodically dials the AB modem (which is connected to a SLC/504)and, using RS Linx with a DDE topic, we log data to an Excel spreadsheet and then save it. The problem we have is that sometimes when the modem dials in to the SLC we may or may not get good data because a particular machine we are monitoring may not be running. I have been asked if we can have the AB modem dial in to the US Robotics whenever the machine starts up so we can get good data. I found a Technote at the Rockwell knowledgebase that shows the necessary programming required to have a SLC automatically dial out. I haven't yet tried it. Has anyone ever done this?

[Chris Elston]

Your idea to have the SLC call home sounds pretty good. I'd be interested in a seeing a link to the tech note that describes what you might be attempting to do. My idea on bad data would have been to try a slower baud rate. I've seen some freaky stuff happen at 19,200K baud over a remote / modem connection. But as soon as I turned the baud rate down to 9600, everthing soothed over. Of course your problem is that the machine is just down and can't make a DDE connection to your spread sheet. So to answer your question, I have not done it "backwards"...SLC calls computer, to be honest I didn't even know that could be done.

[rta53]

Here is the link to the AB Technote. I am planning to try this sometime next week. Modem to Modem

[Chris Elston]

I gotta tell you this... We have a wire EDM here at the shop and those guys want me to come up with something to call a cell phone when the wire breaks. I've done this before for them using: RS Logix Full Version MicroLogix 1000 A Laptop with modem installed MS Excel I connected the alarm signal from the EDM to Micro then used DDE in Excel to monitor the input. Once the input was active, I wrote Visual Basic "send keys" out to the windows 98 dialer to dial a cell phone... However now that I have seen this tech doc, I am going to try my application above with the micro and a modem. It should work.....I'll keep you posted.

[rta53]

I was actually able to get the SLC 5/05 to dial out to my PC running RSLinx using 2 US Robotics modems. I am now trying to do the same thing using the AB modem at the SLC and a USR modem at the PC. Haven't been able to get this to work yet though, go figure. One thing I have noticed is that the modems have to be programmed to a fixed baud rate such as 9600 or 19200 to get them to work.