I need to use a microcontroller to sample a varying analog signal every 5 secs or so, convert it to a digital signal and then output it on a LCD. What I need to do from here is send this same signal to a GPRS modem (on the RTU side) which has a sim card with a static IP, and this data needs to be available for the GPRS modem (on the control room side) to poll and retrieve the data. I am using a PIC16F877 uC and Assembly language to code. However, I am new at this sort of programming, so any help will be greatly appreciated. I have an idea of how to physically interface the uC with the LCD, but I don't know how to interface the uC with the GPRS modem. Please help me out anyone... Thanks.

 

Hello,

If you have TCP/IP stack implemented in PIC, use the PPP. If not, use the modem with the TCP/IP stack like Wavecom.

Regards,
Andrzej
www.modbus.pl

 

Given your "computer" is fairly simple, the easiest (but not cheapest) would be to buy someone else's GRPS module which has an RS-232 port and acts like an old AT/Hayes modem. So you'd issue AT commands to create a TCP connection or send UDP/IP packets, but your PIC just thinks it is serial.

You can try to interface your own "cell module", however many cellular networks require certification at a PRODUCT level, not a module level. So you would struggle to always prove your PIC+module is not going to interrupt the cell networks. Unless you can afford the us$5000 to us$25000 it can cost to pay for that certification, you are wiser to reuse someone else's box product which is already certified.

(We should know - my company uses standard Siemens, Nokia and Wavecomm data modules within our products, yet in EVERY country we try to sell within we need to at least obtain a letter from the 'authorities' acknowledging we can sell & have product activated. In a few countries this is used to make friends rich as it limits the ability for anyone but company X to import cellular data products because 'our standard Siemens' modules somehow fail a test with company X's Siemens module passes - cool, eh?)

 

I have a similar problem.
In my project, I have a GPRS modem (with a SIM card) connected with a RTU (in fact an SLXA). The link between both is Ethernet. The modem has to send the data by GPRS to a server with a fixed IP address.

I think that in the server side an application can easily change in a TCP/IP protocol but what about on the RTU side.
What about the problem about address and protocol??

 

> I have a similar problem. In my project, I have a GPRS modem (with a SIM card) <

The easiest thing to do is to go with a ready solution, e.g., Violasystems.com. With Arctic Router you don't need any AT commands and fixed IP address is provided by a M2M Gateway.