After adding a slave Modbus network, you can use the network’s default “device manager” view to add the appropriate server (slave) Modbus devices.
You need to plan how you are mapping station data into one or more “virtual” Modbus slave devices, including the “virtual”
Modbus data items like coils, inputs, input registers, and holding registers. In the case of a ModbusSlaveNetwork, you may
wish to create multiple “virtual” Modbus slave devices, each with a different (and currently unused) Modbus address. Or, you
may simply wish to have all data to be exposed to a Modbus master to appear sourced from a single (one address) device. In
the case of ModbusTcpSlaveNetwork, although you can add multiple “virtual” Modbus slave devices (with different Modbus addresses)—they
all must be reached through the same IP address as the station.In any case, for any Modbus slave device, you can configure
a number of valid data item “register ranges” for it. In turn, you can then add corresponding Modbus server proxy points under
that device, in order to exchange data with the networked Modbus server.Essentially, you are building a “custom” Modbus device,
and should document its setup (and application) carefully, to make available to the programmer of the master Modbus device.
The following two procedures describe needed procedures:
To add a server (slave) Modbus device in the network
Use the following procedure to add the correct type of slave Modbus device in the network.
To add a sever (slave) Modbus device:
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In the Nav tree or in the Driver Manager view, double-click the slave network, to bring up the device manager (Modbus Slave Device Manager, Modbus Tcp Slave Device Manager). Both of these device manager views operate in a similar fashion.
For general device manager information, see the “About the Device Manager” section in the Drivers Guide.
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Click the button to bring up the New device dialog.
Depending on the network type, the appropriate device object Type will be preselected (either ModbusSlaveDevice or ModbusTcpSlaveDevice).
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Select for number to add:
1(or more, if multiple) and click .This brings up a dialog to name the device(s), enter Modbus device address, and set Modbus Config overrides. Typically, the default values for most items are sufficient to start with, except the following:
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Any ModbusSlaveDevice needs a unique Modbus address (1—247), not currently in use.
For more details on this step, see About Modbus server devices.
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Click to add the server device(s) to the network.
You should see the device(s) listed in the Modbus device manager view, showing a status of “
{ok}” and enabled as “true.”
To configure register ranges in a Modbus slave device
Use the following procedure to establish the “register ranges” for data items in any server (slave) Modbus device. The device’s proxy points must fall within these register ranges, or else they will have a fault status.
To configure register ranges in a server (slave) Modbus device:
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In the Nav tree, expand the slave network, and double-click the slave Modbus device of interest.
Its property sheet show, including 4 “Modbus Register Range Table” container slots with default names “Valid Coils Range,” Valid Status Range,” “Valid Input Register Range,” and “Valid Holding Register Range”.
Alternatively, you can access these container slots when you expand the Modbus slave device in the Nav tree, if you prefer
to work from the Nav side bar.
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Click to expand each of these range containers, and expand the single “Default” register range entry in each. By default, a slave device copied from the
modbusSlaveormodbusTcppalette has the same values for each of the 4 default register range containers: Enabled, Starting Address Offset: 1, Size: 64. -
Make whatever range entry changes are needed, and click .
Note that you can add additional register range entries using the right-click “Add Range” action on any of the 4 register range containers.
For more details, see Modbus Register Range Tables.