GDC 9600RPA modem

Hi,

Anyone ever heard of a GDC 9600RPA modem from General DataComm???

I need to establish communication between a MicroLogix 1100 and a PC with RSView32 via a private phone line using those modems. I want to use DF1 protocol from Allen-Bradley but it doesn't work.

I think the problem is either because of the specification of the protocol (baud rate, number of bits, etc) or because of a wrong pinout...

Any help would be appreciated

Thanks,

Marie

Marie,

The RSLinx DF-1 driver must be configured properly. Also, the problem with connecting a PLC via modem is usually in getting the modem to dial the phone number properly. In many cases, you have to add some special characters (like some commas to create 1-scond pauses at the appropriate time in the dial string), to wait for dial tone, extension numbers, calling card nujbers, and so on. The modem baud rate and other parameters must match the RSLinx settings, of course.

In the instructions below, this is for the modem for the PC (Personal Computer). Here are the RSLinx modem setup instructions (for the computer end). The port, baud rate, and other parameters must match the actual physical modem settings on both ends:

Configure a modem dialer

1 Select Communications > Configure Driver.
2 From the Available Driver Types list, select RS-232 DF1 Devices (point to point), or Rockwell Software DF1 Polling Master device (multi-drop) and click Add New.
3 Enter a name for the driver in the Add New RSLinx Driver dialog box and click OK.

For RS-232 DF1 Devices - In the Configure Allen-Bradley DF1 Communication Devices dialog box, enable "Use Modem Dialer" (second line from bottom of menu), and then click "Configure Dialer".

4 From the Dialer Configuration window, select New > Phone Book.
5 Enter a new Phone Book Name and click OK.
6 Enter a new Name and Phone Number and click OK.
7 Select Configuration > Port to change the Port, Parity, Baud Rate, Stop Bits, and Data Bits, and click OK.
8 Select Configuration > Modem to change the Initialize String, Dial String, Command Mode, Dial Suffix, and Hangup String. The Modem Configuration dialog box also allows you to add or modify the result string the modem returns, or change the timeout and redial number.

9 Click OK to close the Dialer Configuration window.

The modem at the Micrologix 1100 end follows different instructions. You would use RSLogix to set the communications node. In RSLogix, select "Tools", then "Options", then "Systems Communications". Now select the DF-1 node that the modem is connected to (thru RSLinx).

It is often difficult to get both ends working, so I have found it useful (where possible) to set the PC next to the PLC containing the modem, then use a Phone Line Simulator to connect the two and simulate the phone line. That makes it easy to detect what is going wrong. Phone Line Simulators can be purchased online from several places for about $100. Here is one for $79:

http://www.skutchelectronics.com/as-4a.htm

Best Regards, Lancie

Thanks for your help.


Thing is, in my application, there is no dialing to be made, because it is a leased phone line, or private phone line, which means that the connection is continuously opened. That's why I have problems I think. Also I'm not sure about the pinout of the cables I used.

Marie

You could try going on-line or monitoring via the Ethernet port.
of the ML1100.
It may be a lot easier.

Of course I know Ethernet is much easier, but the ML1100 and RSView32 aren't in the same building. The ML1100 is in a water pumping station somewhere in the woods and it would cost about 25 000 canadian dollars to bring optic fiber over there. There is already a phone line so we want to use it to spare money.

Anyways it works now we changed the model of modem (now it's Motorola 9645) and changed some parameters in the modems adn everything works fine here. Tomorrow we will try it on the real site and see if it still works.

Thanks to everybody for the help

Marie

Marie,

I would like to know, for any future similar situation, what modem parameters had to be changed? I would think that you would have to "fool" the modem into thinking that it was "dialing" when actually it would already be connected to the line.

Marie1982 said:

Hi,

Anyone ever heard of a GDC 9600RPA modem from General DataComm???

I need to establish communication between a MicroLogix 1100 and a PC with RSView32 via a private phone line using those modems. I want to use DF1 protocol from Allen-Bradley but it doesn't work.

I think the problem is either because of the specification of the protocol (baud rate, number of bits, etc) or because of a wrong pinout...

Any help would be appreciated

Thanks,

Marie

Click to expand...

Hi - Marie - I know this has been a while - but General Datacomm is still in business and we would be happy to help support you an of our products.
Please contact me for any quesitons.
- Chris