On a Geo SCADA Expert system, you configure the Geo SCADA Expert database so that entries in the database correspond to the plant, control devices, and measuring instruments on your system. This section summarizes the database items that you need to configure to represent the Modbus devices on your system.
In order to represent any Modbus devices, the Simple Modbus Driver has to be installed and running on the Geo SCADA Expert servers on your system. The driver is represented by the Modbus - Simple component in the Geo SCADA Expert Installation Wizard’s Setup window. The component is located within the Server branch of the tree that is displayed in the window (see Install a Driver in Geo SCADA Expert in the Geo SCADA Expert Guide to Drivers).
When you configure Modbus items in the Geo SCADA Expert database, many of the settings for those items need to correspond to the settings of the relevant Modbus devices on your system. Some settings are either fixed (incorporated into the design of the Modbus Slave or PLC), or are configured by an engineer. You need to have access to, or an understanding of, the settings of the Modbus devices on your system before you can configure the Modbus database items successfully.
For example, you need to know the type(s) of communications available for the scanners on your system, and how those communications are structured or grouped.
You also need to be aware of which optional features are required for each Modbus item. These features include:
- Alarm views
- Alarm redirections
- Historic data storage
- User methods.
You can also use core Geo SCADA Expert features with Modbus database items, including Lists, Actions, and Mimics. For actions that are specific to the Simple Modbus driver, see Using Simple Modbus Specific Actions. For further information on actions and details on Lists and Mimics, see the core documentation.
For each Modbus device, you need to configure:
- Simple Modbus Channel(s) to represent the communication connections between a Modbus PLC or Modbus Slave and the Geo SCADA Expert server (see Configuring a Simple Modbus Channel).
You need to configure a separate Modbus channel for each separate communications channel that is available to the Simple Modbus driver on your system.
Check that the channel configuration corresponds to the type of communications being used in each instance (Serial or Modbus TCP).
- At least one Simple Modbus Scanner for each Modbus device that you want to scan.
Configure a scanner for each register range that you want to scan on a device, or each group of points that you want to scan at a different frequency or time offset.
We recommend that you configure separate scanners to scan different blocks of registers in a range, if those blocks are some distance apart. This is more efficient than having one scanner scan a large range that includes many unused registers.
For further information, see Configuring a Simple Modbus Scanner.
- A Simple Modbus Point to represent each item of data that is derived from the content of a Modbus register.
A register can, for example, store the values of analog or digital measuring instruments or control devices that are connected to the Modbus PLC or Slave that is scanned by a particular Scanner (see Points Used on Simple Modbus Scanners).
To minimize the time that it takes to configure the required Modbus items, you may want to configure them in the order listed above, as Scanner configuration requires you to specify a channel, and Point configuration requires that you specify a scanner, and so on.