The Advanced Modbus driver supports four types of Advanced Modbus outstation set:
- Advanced Modbus Direct Outstation Set—A set in which the controllers use a single channel to communicate with the server.
You need to configure one Advanced Modbus Direct Outstation Set for each group of Modbus controllers that communicate via a particular direct channel.
- Advanced Modbus Shared Outstation Set—A set in which each controller can communicate with the server using either of two channels. Each controller in the set can use either channel.
You need to configure one Advanced Modbus Shared Outstation Set for each group of Modbus controllers that communicate via, and share, a particular pair of direct channels.
- Advanced Modbus Switched Outstation Set—A set in which each of the controllers communicate with the server using one of two channels. All of the controllers in the set use the same channel.
If Geo SCADA Expert detects that the channel in use has failed, or that a specified number of controllers have failed, Geo SCADA Expert will switch the controllers to communicate using the alternative channel.
You need to configure one Advanced Modbus Switched Outstation Set for each group of Modbus controllers that communicate via, and can switch between, a particular pair of direct channels.
Modbus controllers support master station switching of channels on switched sets.
- Advanced Modbus PSTN Outstation Set—For Modbus controllers that connect to Geo SCADA Expert via the telephone network, using an individual or shared modem.
You need to divide any PSTN controllers into groups and create one Advanced Modbus PSTN Outstation Set per group (see Configuring an Outstation Set).
In each case, you specify the features for a set by using the fields on the appropriate Advanced Modbus Outstation Set Form.
Each Form has several tabs.
Use the Modbus tab to:
For Advanced Modbus Outstation Sets other than PSTN, also use the Modbus tab to:
- Specify Whether a Set Broadcasts Set Clock Messages
- Specify Whether a Set Uses Unique Modbus Addressing.
Properties on other tabs are common to outstation sets on many advanced drivers—for information, see Tabs on Outstation Set Forms.