SLC-5/04 to modem


Thread Starter

Robert Larson

Need information on connecting A-B SLC-5/04 to a USRobotics 56k sportster external modem. Modem initializing strings, dip switch settings, and cabling info would be appreciated.

Robert Larson
[email protected]
We tried connecting "ordinary" modems to a SLC5/04 with no success. I would suggest buying a Rockwell CH0RAD. This will allow you to connect to chanel 0. Or optionally a Miille Applied
Research 166-100. We've used both and the additional cost of the hardware is more than made up for in the reduced set-up time (and headaches). We've had success with both. Hope this helps.

Brady Matherne
Panel Specialists, Inc.
[email protected]

Derrick Stableford

Also try a company called Westermo, they have a pretty good free tech handbook on connecting to all sorts of PLC kit.

D Stableford
TE Controls, Castle Donington, UK
[email protected]

David Messing

Hi Robert

I have seen it done. We recently had a new power plant built using Fairbanks Morris engines. A SLC50/04 is used to control the dual fuel. They use a 56K US Robotics Sportser, but set the dip switches special for the operation and don't use the modem for anything else. They call the modem and the modem is directly connected to the RS-232 serial port on the AB PLC. When they need to troubleshoot the PLC ladder or make changes, they have us unplug the MMI interface and connect the modem to the PLC's RS232 port.

David Messing
Nebraska City Utilities
Also look at Tomantron's Muxiport which has app notes for connecting to an ordinary modem to their port multiplexer which allows simultaneous modem connection and PLC programming connection.

Dan McGrath

Fred Chwalek

I suggest disabling all flow control in the modem, either with dip switches or init string. You will need the command set from USRobotics that works with their modem. On the internet go to website and look for your modem support. Let the PLC system handle flow control. This may require jumping RTS and CTS to get the RS232 port to transmit.

I have extensive experience with US Robotics and 5/04 processors. I tried sending a message previously, but it did not make it to the list.

It is certainly possible to use the US Robotics (and now 3COM) modems for this purpose. If you use Win 9x or NT 4.0, I can help you with the modem init stings. I like to use Hyperterminal for this purpose to store the init string in the modem's NVRAM.

I routinely use APS and RSLogix500/RSLinx for modem troubleshooting in SLC 5/04 processors located in Brazil, Canada, Germany, Mexico, and the USA. I would like to help.

There are some questions that I need answers to.

Where is the modem located? (USA, other country)

What baud rate have you configured the SLC program for?

With this info I can post a string for you here, or send you a pre-configured Hyperterminal file if you let me know what comm port you will use to communicate with the modem. (You must be able to connect directly to the modem with your pc for setting the NVRAM.)

Note that, other than auto-answer, the US Robotics modem factory settings are usually close enough right out of the box. Default settings normally allow the calling modem to request the baud setting for the answering modem.
Also note that there is more than one type of 56K external sportster. I assume the dip switches you mention are those on the modem. What is the
model number? Yes, in case you are wondering, there are different dip configurations, depending upon the specific Sportster!

The tricky part is not to set up the modem. Rather it is to set up the SLC program.

Normally, the modem is connected to SLC-5/04 RS232 port and powered up when it is time for a modem session. This is not the only way, the modem can be connected continuously.

Manoj Mathew

I am using normal Acer modem to communicate to a GE Fanuc PLC over the standard landline telephone system. Though not with Allen Bradley, the principle should be the same. Worth a try. Connect the modem to a computer, open hyperterminal and give the following commands: AT&FS0=1&D0 AT&W (the commands are for 1. reset the default values 2. set auto answer after one ring 3. disable DTR control 4. Save to temporary non-volatile memory) Now connect the modem's RS232 port to the AB's RS232 port and the tel. line in. From the computer connected to a modem on another line, open hyperterminal and "connect" to the modem at 9600baud, 8 bits, No Parity, No flow control. Now issue the following command on the hyperterminal window: ATDT n where n is the telephone number of the modem at the PLC end. After the line connects, close the hyperterminal window (say yes when it asks if you want to disconnect.) The hyperterm connection to local modem is closed but the modem to modem connection retains since DTR is ignored. Open RSLogix and connect (autoconnect) on the COM port connected to the modem. To close communications, go offline on RSLOgix, reopen hyperterm and type: +++ ath ath0. Alternately, if the local modem is an external one, disconnect its power. Try this procedure if it works. Manoj Mathew. [email protected]