When using the PM5560 as a Modbus gateway there may be excessive timeouts for downstream devices.

Issue:
When using a PM5560 as a Modbus gateway you may notice there are excessive timeouts communicating with some or all of the downstream devices. Any other PM5000 series meter on the communications chain including the gateway meter may appear to respond normally.

Product Line:
PM5560 Series Power Meter
PM800 Series Power Meters
CM4000 Series Power Meters
CM3000 Series Power Meters
Power Monitoring Expert (PME) 8.x
Power Monitoring Expert (PME) 7.2.x
StruxureWare Power Monitoring (SPM) 7.0.x

Environment:
Power Monitoring and Communications

Cause:
There is an issue with the PM5560 meter when used as a Modbus Ethernet gateway access to serial devices connected to the meter's RS-485 serial communications port that have scattered read support.

Resolution:
*Warning: Take backups of any files prior to modifying them. Ensure the backups are in a location that will not be overwritten (i.e. the Desktop).

There are three known workarounds listed in order of recommended implementation. If the first workaround does not work or is not feasible to implement move on to the next option.

1. Change the baud rate to 38400 on the gateway and all downstream devices. This will improve the throughput of the PM5560 Ethernet gateway and eliminate most timeouts from downstream devices.
The maximum distance of the 2-wire RS-485 daisy chain when using a baud rate of 38400 is 1,500ft for up to 8 devices and 1,250ft for between 9 and 16 devices.

2. In the event that the customer cannot increase the baud rate of the existing RS-485 daisy chain, apply the following workaround

1. Locate the .xml device driver file/s of the device/s associated with the communications timeouts. ie. "...\Schneider Electric\Power Monitoring Expert\system\translators\PM800.xml"
2. Open the file for editing and use the search function to locate ScatteredReadSupported="1" and change this to ScatteredReadSupported="0"
3. Save and close the .xml file.
4. Restart the "ION Site Service"

3. If the workarounds above do not resolve the issue you may leave scattered read support enabled and lower the Max read requests to 9.

1. Locate the .xml device driver file/s of the device/s associated with the communications timeouts. ie. "...\Schneider Electric\Power Monitoring Expert\system\translators\PM800.xml"
2. Open the file for editing and use the search function to locate MaxRequestRegisters= and change this to MaxRequestRegisters="9"
3. Save and close the .xml file.
4. Restart the "ION Site Service"

It is only recommended to modify the device driver files if updating the baud rate of the gateway and downstream devices is not an option as editing the driver files is a global setting and will affect all communications with the updated device type.

Released for:Schneider Electric United Arab Emirates