Modbus settings in manual mode

The Atom series controllers provide the ability to connect devices using the RS-485 interface (Modbus protocol).

Note: The values of the speed, parity, stop bit, and slave address fields are specified by default, and the register numbers, register type, function type, data type, and byte swap are specified in the technical documentation of the device that is connected to the controller via the RS-485 interface.

Sometimes information about the byte swap is missing in the documentation. In this case, this value should be selected experimentally, focusing on the correctness of the obtained value when displaying it.
As a rule, the device's slave address and speed can be changed either by writing certain values to the service registers, or by changing the configuration of the DIP switches on the device itself according to the instructions.


Go to controller settings

To configure the input ports, you must first go to the controller settings:
● Go to Menu - Device Manager
● Select the controller to which the RS-485 bus is connected from the list and click Setup



Go to interface settings

● Select the Ports and interfaces and go to the Interfaces tab● The tab shows the RS-485 bus as a card



Selection of the controller's operating mode

● Click on the RS-485 card● Select the Master mode of operation● Click Save



Advanced interface settings

● Select the "gear" icon (advanced settings)● You can specify following values here:
- timeout - data update interval
- speed - bus speed in bit/s- parity- stop bit Save the settings by clicking on the icon and return to the settings window



Choosing a slave device

● Select the Slave device card● Press + in the upper right corner● Select Manual configuration



Setting the register of the peripheral device

● Specify the slave address of the connected device● Specify the register from which you want to get data (and/or write data)



Device display settings

● Enter the device name (optional step)● Select the type of connected device (values and units of measurement will be displayed depending on the selected type)● Specify the room the device is in (optional step)



Setting data reading parameters

● Select the register type - Input, Discrete input, Coil, Holding● Select the function type - Read, Write Single, Write Multiple, Read Write Single, Read Write Multiple



Setting data reading parameters

● Select data type - Boolean, Unsigned Integer 16, Signed Integer 16, Unsigned Integer 32, Signed Integer 32, Float● Select byte swap - AB, BA for 16-bit data types, ABCD, BADC, CDAB, DCBA - for 32-bit data types



Advanced config for reading data

● Select the "gear" icon (advanced config)● You can specify a value here update period - data update interval
- multiplier - the number by which the register value must be multiplied to get the correct value. For example, the value of the measured temperature is often stored in the register as a number without a decimal point (if the temperature is 20.5°C, then the register will contain the number 205). In this case, to get the real temperature value, you need to apply a multiplier of 0.1
and, if necessary, offset - correction of displayed data


Advanced settings always contain data by default. Changing the values in the advanced settings is an optional step if necessary.
In case the desired data is placed in several registers of the device, repeat steps 5-10 for all registers.

The result of the described steps:

● The device on the RS-485 bus is configured and ready to use. You can view and change register values by going to the Dashboard tab. If multiple registers are configured, they will appear as different devices.

Important! If the device is not physically connected, or the electrical contact on the connections is broken, it will be displayed in gray as inactive in the list.

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