Basic Modbus RTU configuration to read a register from PM800 Power Meter.

Issue

Basic Modbus RTU configuration to read a register from PM800 Power Meter.

Product Line

SmartStruxure Solution

Environment

  • Automation Server
  • Modbus RTU
  • PM800 Power Meter

Cause

Integrate power meters to a SmartStruxure front end for the user to view data and trend logs.

Resolution

Here are the steps to Configure a ModBus RTU interface in SmartStruxure to read the Line Voltage register from a PM800 Power Meter.

(Assuming meter has already been properly wired to one of the serial ports on the AS)

  1. Create the Modbus Interface, in this case a Modbus Master Network.

 

Link the interface to a serial port in the AS in the Port Reference field, in this example to RTU device is wired to RS485-COMB

2. Under the interface create the RTU device.

In this example the device id is 11, enter the appropriate id for the device.

Once the device object is saved, the status should show 'Online' unless there is a communications issue.

You can confirm that SmartStruxure is able to correctly detect the comm status of the device by disconnecting it from the commport and observing the status change to 'Offline', upon re-connection the status should once again display 'Online'

3. Under the device create a Modbus Point of type AnalogInput to get the value of the Line Voltage from the device. According to the documentation for the PM800 the register holding the line voltage is at 1124

The value of the point should now correspond to the line voltage in this case 125 volts.