Metz Connect MR-AO4 Modbus RTU

Installation

1. 1Mount the Metz Connect MR-AO4 on a DIN TH35 rail inside the distribution cabinet and wire the analog outputs to the target actuators.
2. 2Connect the RS-485 A and B terminals of the MR-AO4 to the RS-485 port on your ModbusCloud gateway (MCG or MLP series).
3. 3Set a unique Modbus address and the baud rate to 9600 using the two rotary switches on the front panel of the module.
4. 4Use the Metz Connect MBus configuration tool to select the correct output type (voltage or current) for each channel.
5. 5Import the Metz Connect MR-AO4 template in the ModbusCloud portal and assign it to the gateway with the matching Modbus address.
6. 6Verify communication by writing a test value to one of the four analog outputs and confirming the actuator responds.

Things to watch for

01

The gateway cannot communicate with the MR-AO4. What should I check?

Verify that the RS-485 A and B wires are not swapped and that the baud rate on the module matches 9600 as expected by the template. Also confirm the Modbus address set on the rotary switches matches the address configured in ModbusCloud.

02

How do I change the output type from voltage to current?

Use the Metz Connect MBus configuration tool connected via RS-485 to set the output mode for each channel. This cannot be done through Modbus registers alone.

03

What value range should I write to the output registers?

Each output register is a uint16 at addresses 0 through 3. The exact scaling depends on the configured output type. Consult the MR-AO4 datasheet for the mapping between register value and physical output level.

04

Can I use multiple MR-AO4 modules on the same RS-485 bus?

Yes. Assign each module a unique Modbus address using the front panel rotary switches. Add a separate template instance in ModbusCloud for each module with the corresponding address.

Registers (4)

0 read / 4 write

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