Two way control via SMS

Hi there,

I want to command a PLC controlled plant system remotely with the help of an SMS using GSM modem.

The user should be able to control the start/stop of the plant pumps as well as verify the status of them via a set of pre-programmed commands through SMS.

Can anyone please help me out in this regard??

r u gonna connect the gsm modem to a microcontroller?? i hope it contains a controller!

PLC<--->Microcontroller<--->GSM modem
but do you know how to send commands serially to PLC

you might need to re-program your PLC but this can be complicated as PLC are designed specifically sometimes. need more info on your PLC