The optimal choice for all wireless SCADA system is to use the Motorola RTU with the MDLC (Motorola Data Link Communication) protocol, which help to ensure optimal reliable wireless and system characteristic SCADA communications.
The customer or system architect must carefully select the most suitable SCADA communication protocol for his application in systems where it is essential to use the GPRS network where no other solution is available. The GPRS protocol stack allows network operators to implement IP based core architecture for data applications.
Simple GPRS modems have limitations, as they can not transfer DNP-3 or Modbus protocols. RTUs must be interfaced to more advanced type of GPRS modem using standard IP communications over serial link and point to point protocol in order to accommodate these SCADA protocols.
The ACE3600 RTU with its MDLC protocol provides an advanced, effective and flexible solution for communication and the implementation of the ACE3600 protocol stack for GPRS strictly adheres with standard UDP/IP/PPP as defined for SCADA protocols over IP networks.
All communication related MDLC layers remain intact while operating over the IP levels and GPRS physical. This solution allows retaining a reliable operating communication link to appear as a transparent link completely in the MDLC network.
The proposed ACE3600 RTU based solution over GPRS is different significantly from GPRS networks operating with DF/1 or Modbus. These protocols have only three layers: Link, Physical and Application. When simple RTU or PLC devices are connected to the GPRS modem, it necessitates configuring the modem for non transparent mode and uses the full GPRS IP stack. Then the performance of SCADA systems built with PLCs remains limited to the functionality supported by the PLC, such as:
• Polling only for data collection by the SCADA master
• Local configuration and programming
• Limited capability to correct errors
• Use of a single type of media communication