Master-Slave Communications

Most drivers enable Geo SCADA Expert to be the SCADA Master. When the Geo SCADA Expert serveris the master, Geo SCADA Expert initiates and controls the transmissions to and from the other devices on the system. (The exception to this being any outstation that has the ability to send unsolicited messages to Geo SCADA Expert, to inform the server of any new alarms that have been generated at that outstation.) When Geo SCADA Expert is the master, any sensors or control devices are represented by points in the Geo SCADA Expert database. The driver-specific documentation specifies which type(s) of point are supported by each driver and explains how to configure those points. For general information on points, see the Geo SCADA Expert Guide to Core Point Configuration.

Some drivers enable Geo SCADA Expert to be a Slave. When Geo SCADA Expert is a slave, the server acts like an outstation and reports any changes to another SCADA master. The SCADA master may be another Geo SCADA Expert server, or a third-party server. When Geo SCADA Expert is a slave, any ‘point’ data is mapped into a simple block of memory in the driver, using a Value Map or Filtered Value Map (see Configuring Value Maps in the Geo SCADA Expert Guide to Core Configuration). The driver-specific documentation specifies which type(s) of Value Map and/or Filtered Value Map a particular slave driver supports.

If a Geo SCADA Expert driver is a slave driver, the word ‘Slave’ is included in the driver name. Drivers that do not include the word ‘Slave’ in their name typically enable Geo SCADA Expert to be the SCADA Master.

With any Geo SCADA Expert driver, refer to the driver-specific documentation for information on which database items you need to configure in Geo SCADA Expert, in order for Geo SCADA Expert to be either the SCADA Master or a Slave.

Be aware that it is possible for Geo SCADA Expert to be both a SCADA Master and a Slave, if both master and slave Geo SCADA Expert drivers are installed on a system.

The diagrams in the remainder of this section demonstrate each of the above setups:

• Geo SCADA Expert Configured as a SCADA Master
• Geo SCADA Expert Configured as a SCADA Slave
• Geo SCADA Expert Configured as both a SCADA Master and a SCADA Slave.

Be aware that these diagrams are very simplified versions of each system—a Geo SCADA Expert system typically comprises one or more servers (of which one will be ‘Main’) and multiple ViewX and Virtual ViewX clients (user workstations). For more information, see Understanding Your System in the Geo SCADA Expert Guide to ViewX and Virtual ViewX clients. For more information on server setups, see System Architectures in the Geo SCADA Expert Guide to Server Administration.

Further Information

Set up the Drivers on a New Geo SCADA Expert System.

Add a New Driver to an Existing Geo SCADA Expert System.