Wireless modem

Hi Guys,

My setup is as follows,

Micrologix 1500LRP - connected via serial cable to a Juni CDMA wireless modem.

My problem is that i cannot connect to the plc from my laptop modem via the wireless modem.

The modem rings and connects (confirmed in hyper terminal by using another laptop on the wireless modem's serial port),
but my laptop does not establish a connection through rslinx.

I can send an ascii command from the plc via serial cable to the modem to ring my mobile so i think the comms/cable is ok.

I have got both the plc and modem set at 19200 baud rate.

I have set the driver in rslinx as a rs232 df1 device/full duplex.

Just wondering if anyone has had similar problems or knows a bit more about setting this up. Any advice would be appreciated.

Brijacq

You mentioned being able to send ASCII strings out the serial port; do you have the port set to ASCII mode, or did you just send the string out unidirectionally in DF1 mode ?

I have had trouble with cellular modems before; sometimes they try to use data compression that messes up DF1 protcol, or they require very long connection times between packets, which also doesn't work well with a protocol that requires a simple ACK packet after every data transmission.

You might have to put a serial analyzer (heck, even Hyperterminal) at the PLC end to see what data (if any) is coming through the modem pair from RSLinx.

I might be barking up the wrong tree here but I recently had trouble connecting up a dial up modem. I n the process of trying to get it working, I must have read every item on the regarding PLCs and modems. I came across one about connecting an Omron PLC vis a GSM modem. and it was saying that the GSM network often wont support certain protocols such as 7 bit, even parity, 2 stop bits, and that you need to change it to 8,0,1. I don't know if this applies to you but theres my two cents worth anyway

Peter

Is this a GSM wireless modem? Don't know if this helps Brijacq, as well as all the points above, but it caught me out a few times when i started using these. The mobile number associated with the SIM card has to be the DATA number, NOT the voice number you would normally dial to talk to the card. The network that provided the card should give you this, or i think there is an AT command (CUSD i think???) you can fire at it to check.....Hope this helps!:nodi:

Thnx for the replies guys,

Still no comms as yet. I have contacted Rockwell tech and they say the modem is not returning a carrier signal, and i have talked with the modem manufacturers and they say the modem is trying to make a PPP connection and needs a RAS application to make it answer. I dont think the Micrologix can give it this signal. So i am still a bit stuck. I will update on any developments for future reference.

brijacq

PS The modem is connected to a 1 meter antenna and i was supplied with only 1 number. As you say this could be the voice number but not sure.

WE HAVE COMMS It was a couple of settings in the modem all along. I had to use the command (via hyperterminal) AT$QCVAD=4 this makes the modem enable incoming connections for async calls. I also had to use the AT&D0 command to ignore DTR so it would hold the line with nothing connected to the modem on the serial port (or the micrologix in this case).

brijacq

Good news, glad you sorted it!!

Just for future reference (if anybodys interested?) the command to report all numbers associated with a SIM card is

AT+CUSD=1,*#100*# <CR>

This should return the VOICE, DATA, and FAX numbers (if assigned).

May help somebody else......