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ION over Modbus communications for PM8000 and ION7400 series meters

New features and improvements were made on firmware version v1.4.1 for the PM8000 and ION7400 meters. This attached document (TechnicalBulletin_ION-Modbus_v1.3) addresses issues related to replacing legacy products on a Modbus serial (RS-485) bus connected to PME systems.

ION over Modbus is a communications method that allows an ION master such as EcoStruxure™ Power Monitoring Expert or PowerLogic™ ION Setup software full access to all the ION modules inside the ION meter, while communicating using Modbus RTU protocol on the serial daisy chain.

The primary use of ION over Modbus is specifically for retrofit applications, where a Modbus meter such as the PowerLogic PM800 series meter is being replaced by an ION meter such as the PowerLogic PM8000 series meter on the RS-485 serial bus.

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ION masters such as Power Monitoring Expert (PME) and ION Setup use ION protocol to communicate with an ION meter to access and manipulate the ION modules in the meter.  However, if the ION meter is added to a Modbus serial daisy chain, the ION meter must be configured as a Modbus device (i.e., protocol set to Modbus RTU) to allow Modbus masters access to the mapped Modbus registers in the ION meter.
PME and ION Setup use Modbus protocol to communicate with a Modbus gateway and the serial daisy-chained meters.  Historically, an ION meter that has been added as a Modbus RTU device in the Modbus serial daisy chain cannot be easily configured, i.e., PME or ION Setup cannot access the ION modules in the meter because the communications protocol is set to Modbus RTU, not ION. 

All ION meters support the Modbus RTU protocol. Newer ION meter firmware adds ION over Modbus functionality. This enables an ION master such as Power Monitoring Expert or ION Setup to access all configuration and historical data in the meter while it is connected to a serial communications bus and configured as a Modbus RTU device

Updates are available for Power Monitoring Expert and ION Setup to support ION over Modbus for communication networks utilizing an Ethernet to serial gateway device to connect to the serial daisy chain.

Power Monitoring Expert and ION Setup currently do not support ION over Modbus communications for:
  • Direct Ethernet or direct serial communications connections.
  • Serial communications sites that use serial-to-serial communications converters such as an RS 232 to RS 485 converter or USB to RS 485 adapter.
  • Modem sites (telephone, radio or fiber optic).
Serial communications considerations
ION meters can generate larger volumes of historical data, events or waveforms, which might cause communications performance issues.  It is recommended not to exceed 10-15 devices wired on the same RS-485 daisy chain.

To use ION over Modbus, both your ION meter and ION software must meet the minimum requirements:
ION meter
  • PM8000 firmware v1.4.1 or later
  • ION7400 firmware v1.4.1 or later
ION software
  • Power Monitoring Expert 8.2 CU1  (Cumulative Update #1) or later. This update is available for download from this Box link.
  • The latest version of ION Setup (available from Box at Schneider electric)

For more information on ION over Modbus Communication, review the attached Technical Bulletin.
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