UNITRONICS
GPRS
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.
GPRS & Unitronics OPLC
After 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 other
Unitronics' communication utilities.
 Log PLC data via the DataXport utility.
GPRS & Unitronics OPLC
 Connect to SCADA via UniOPC server or Modbus
 establish connection between Unitronics OPLCs and transfer data
(using for example MODBUS protocol).
Before We start…
Requirements:
 GSM Modem which supports GPRS
functionality. Currently Vision
OPLC can work with list of modems
 GPRS service must be supplied by the
user's cellular service provider
 The GPRS modem must be prepared
to PLC side
 PC with direct internet access using
public IP
Registration
Before exchanging data, OPLC must register to the provider’s cellular
network.
Registration
After 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.
Listen
Sometimes 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.
End connection
When 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.
Thank you!