I have an AB MicroLogix1500 PLC (with LRP processor). I want to connect a Wavecom GSM modem to it to send SMS containing alarms. I want to transmit a string to the LRP port (containing the AT command + parameters) but i need to append some keystrokes to it, like carriage return <CR> and <ctrl-Z>. How am I going to do these???

 

^M is the carriage return command
I assume your using CRTL-Z as an end of command or string function? or is this the break or esc function? which is %E2 (break)

Check with your modem manufacture as these are the Hayes command set codes.
You can also use S3,1 = 1 CR , S4,1 = 1 LF

need more basic information go to
http://www.acl.co.uk/modem.htm

matt

 

Have not used these devices for this purpose before but have used other brands.
I have only ever had to write modifications to the modem via hyper terminal and then programme the PLC with the transmit command to the serial port. just beware you send the correct number of bytes in your header.

 

The last time i used at/?. That gave me all of the commands. Some modems you have to use (&f, #f or %f) to (reset) the modem. I do not think that you can not share the modem when you use the AT commands. The best ocx driver then I found on i-net was NETPOINT.

Netpoint Computers Ltd
www.netpoint.co.uk

 

Eric----

In your String data, enter control characters by using a backslash and the two-digit hexadecimal representation of the character. (You need an ASCII table.)

CR is \0d
LF is \0a
<ctrl-z> is \1a

Hope this helps!

Larry Lawver
Rexel / Central Florida

 

I am looking into the same thing (slc talking to a usr modem using ascii write in plc). Just starting looking into and getting no where fast. Any thing you can help me with?

Thanks,

 

All modems utilize the Hayes command set, all have more or less registers and special functions / commands. So, get the command set for your modem, get a copy of the ASCII code set (found in any good computer booklet or on the web)and program your heart out, it really should not be that hard.

matt

 

Hello everybody. I'm searching the internet on this moment, because i'm searching to the same solutions as Eric. I must make for my thesis the same installation that also will send an alarm messages from a PLC, with a GSM-modem to a GSM. The only different is that we will use a Siemens S7 400. But I guess that that isn't that different. We still don't know how we must created the serial communication between the modem and the PLC. Did yours installation already works? Because I did't know how i must do it? You can always contact me by my mail: [email protected]

Greetz
Geert