Issue
Is it possible to communicate with PM8000 meters daisy chained via the Ethernet port with ION protocol (port 7700), simultaneously with RS-485 serial port daisy chain to communicate with Modbus protocol (port 502)?
Product Line
PM8000 Series
PM8240
PM8243
PM8244
Environment
Meter Communication capability
Modbus Gateway and Ethernet ION Communications
Modbus Master and Modbus Slave
Cause
A third-party software is being used to communicate with meters with Modbus protocol, while the PM8000 meters are daisy-chained via the Ethernet port to communicate with PME software with ION Protocol
Resolution
Yes, it is possible to daisy chain PM8000 meters via the Ethernet port to communicate with ION Protocol, and use the RS485 serial port to act as a Modbus Gateway on the first meter, and Modbus RTU for the rest of daisy-chained slave devices.
Note: 8 simultaneous connections can be used by ION, Modbus TCP, Modbus RTU over Ethernet, or DNP.
In a Modbus gateway configuration, a Modbus master device can communicate using Ethernet through the gateway meter to downstream serial devices.
A Modbus request is sent through Ethernet using Modbus/TCP to the gateway meter. If this request is addressed with the slave ID of one of the downstream serial devices, the meter forwards the message to that device using Modbus RTU. When the downstream device responds, the gateway meter forwards the response back to the 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.
For Modbus gateway, you must wire the serial Modbus slave devices, configure them and connect them to your Ethernet-connected Modbus gateway meter. Ensure that each serial device is configured to communicate over Modbus with the same baud rate and has a unique unit ID. Configure the gateway meter's serial port to use the Modbus master protocol and enable the Modbus gateway feature.
The meter supports up to 32 devices serially through the RS-485 port.
This article, FA212335, shows the total allowable simultaneous connections on ION meters.
This article, FA244498, is a FAQ for the PM8000
