PM8000 Modbus Gateway Function - Question ?

[Rich_Lannaghan]

We seem to be struggling here with a PM8000, we have set it up as a Modbus gateway as per the below, we are in the situation where we can see the downstream devices and read data but cannot retrieve anything from the meter itself over Modbus TCP, Modbus poll and other test tools just give us a device busy error ?

Have we missed a step or is there anything special we need to do to read the meter itself over Modbus TCP and read the slave devices or is this functionality not supported ?

Configuring a Modbus gateway using ION Setup

You can configure Modbus gateway on your meter using ION Setup.

Connection type Configuration

Serial connection Select the serial communications port that is connected to the Modbus slave devices from the

Assigned Port list.

TCP connection Enter the IP address of the Modbus slave device, making sure that the IP port is set to 502.

7EN02-0336-00 93

PowerLogic PM8000 series user manual Chapter 12 - ION Setup

Before you begin, make sure you have completed the following tasks:

• Confirm the serial network of devices are wired and configured to have the same

baud rate, serial port settings (for example, 8N1), and protocol (Modbus).

• Confirm each serial device has a unique unit identifier.

• Confirm the serial network of devices are connected to the gateway meter’s serial

communication port.

• Confirm your gateway meter is communicating over Ethernet.

1. 1. Start ION Setup.
2. 2. Open the Setup Assistant for your meter.
3. 3. Navigate to Communications > Serial settings and select the tab for the

communications port that the serial network is connected to.

1. 4. Select Protocol and click Edit. The protocol selection screen appears.
2. 5. Set the protocol to Modbus Master.
3. 6. Navigate to Communications > Network settings and select the TCP/IP tab.

Select Modbus Gateway and click Edit. The Modbus gateway selection screen is

1. displayed.
2. 7. Select the communications port that the serial network is connected to (and you just

set to use the Modbus master protocol) and click OK. The Modbus gateway

connection is created.

1. 8. Create an Ethernet gateway site to access the serial network of devices through your

gateway meter.

[Rich_Lannaghan · Accepted solution]

OK, so it seems we have sorted it, by reading the manual.....

Modbus master. In addition to Modbus slave addresses 0 - 247, the Modbus gateway

supports slave address 255, which sends a Modbus request to the gateway meter only.