2 About GPRS GPRS - General Packet Radio Service GPRS is packet based wireless communication service offered by some GSM cellular providers.GPRS promises continuous connection to the Internet via cellular network for mobile phone, computer users and PLCs.With GPRS connection, the user pays for transferred Kbytes and not for call time. In theory GPRS packet-based services cost users less than circuit-switched services.
3 GPRS & Unitronics OPLCAfter GPRS connection established between PLC and PC you can use Unitronics software to:Download, upload, and edit the controller program.Read and write data to/from controllers via Remote Access or otherUnitronics' communication utilities.Log PLC data via the DataXport utility.
4 GPRS & Unitronics OPLC Connect to SCADA via UniOPC server or Modbus establish connection between Unitronics OPLCs and transfer data(using for example MODBUS protocol).
5 Before We start… Requirements: GSM Modem which supports GPRS functionality. Currently VisionOPLC can work with list of modemsGPRS service must be supplied by the user's cellular service providerThe GPRS modem must be prepared to PLC sidePC with direct internet access using public IP
6 RegistrationBefore exchanging data, OPLC must register to the provider’s cellular network.
7 RegistrationAfter successful registration the controller will receive IP address. This address usually is temporary – each time you register you receive new IP.The IP address is one of the provider’s LAN. Usually, without special agreement with the provider, you cannot access this address from outside LAN.That’s why the standard procedure is, when the controller calls the remote PC.The remote PC needs to be already in Listen mode.
8 ListenSometimes you will want to exchange data between two controllers or controller and other device, located in the same LAN.In some cases, after agreement with the provider, it’s possible to access the controller from outside cellular LAN.In this cases the OPLC can be configured to Listen mode.
9 End connectionWhen we want to end the data transfer with specific device, we perform End Call.If our device is in Listen mode, we can Stop Listen.We can end the session with Unregister from network.