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Using EHS6T with Unitronics Unistream PLC (AT&T SIM) | Thales IoT Developer Community

August 16, 2018 - 4:24pm, 1017 views

A customer of mine was sold a Unitronics PLC with an EHS6T modem with the understanding that he would be able to send emails from the PLC.  I am a PLC expert, not a GPRS modem expert, but I have spent over 30 hours on trying to get this project to work, and I am stumped.  The PLC uses two instructions, one to initialize the modem, and the other to initialize the GPRS.  I only have a few variables that I can modify.  They are labled and filled in below:

Pin Code

GPRS APN     wap.cingular


GPRS Password   cingular1

The Init Modem command replies that it is successful, but the Init GPRS command fails every time.  There is no diagnostics on the PLC, so I have been using AT commands to try and figure out what is wrong.  I have also called AT&T, and they claim that the SIM card is provisioned correctly.

Here is my question, what AT commands can I use to find out where the problem lies?  Thanks in advance for any help you can provide.