I/O IP Modules - Modbus Gateway - Preparation for work

he following document takes up the topic of how to prepare iSMA-B module with IP to work as Modbus Gateway in a few steps.

In iSMA-B modules with IP, the Gateway Modbus TCP/IP to Modbus RTU is continuously enabled by default and it works regardless of whether the Modbus or BACnet protocol is set on pins 4 and 5 of the 'DipSwitch' switch (S3).

To start iSMA-B module with IP to work in Modbus Gateway mode, it is necessary to perform the following steps:

1. Disassemble the front panel of the iSMA-B device with IP, locate the mini USB port and connect the cable to it, then connect the other end to the PC.

2. Run iSMA Configurator software, which will automatically detect the connected device and place it in the tree under the 'USB' item.

NOTE: iSMA Configurator may not detect the device when Sedona Updater or FCU Updater is being used at the same time. The same behaviour may occur also when only iSMA-B-FCU or iSMA-B-AAC20 is connected to the PC.

3. In the next step, select the automatically found device and click the 'Switch To Online' button and go to the 'IP Configuration' tab.

4.In this tab you can change the default settings of the Ethernet network card and the communication port, as well as 'RS485 Timeout [ms]' and 'Modbus TCP Timeout [s]' which are respectively the frame loss time parameters on the RS485 bus and socket TCP closure.

Figure 1. Configuration of the ‘IP Configuration’ tab in iSMA-B module with IP using iSMA Configurator.

5. After setting your configuration, click the '! Reload Settings!' Button, it will load the new settings to the device.

NOTE: the '! Reload Settings!' lights up red after entering new values ​​in the device configuration.

6. In case of changing parameters from the 'IP Configuration' tab, you will additionally need to restart the module - to do this, right-click on the device in the tree and select 'Reset Module'.

7. If the devices in the RS485 network, which is to be operated by the iSMA-B gateway with IP, are configured with the '8N1' value and '0ms' response delay, it is enough to adjust the communication speed using the 'S3' 'DipSwitch' (pins 1-3) as well as the Modbus address of the gateway with rotary switches 'S1' and 'S2'. However, if you need to change other default settings, go to the 'RS485 Configuration' tab in iSMA Configurator and perform further steps.

Figure 2. Configuration of the 'RS485 Configuration' tab in iSMA-B with IP module using iSMA Configurator.

8. In this tab, you can change the parity settings, the number of data bits and stop bits, as well as the so-called user communication speed, 'User baud rate' (which can be used when pins 1-3 of the 'S3' 'DipSwitch' are in the 'OFF' position) and the response delay.

9. After setting your configuration, click the '! Reload Settings!' button, it will load the new settings to the device.