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9–2 P485 MODBUS TO PROFIBUS CONVERTER – USER GUIDE
APPLICATION EXAMPLE
SYSTEM SETUP This chapter describes how to set up the P485 with MM2 relay and PQMII meter to read
and write parameters. It can also be used as a guideline to setup the P485 Modbus to
Profibus Converter for communication with any GE Multilin relays.
The PQMII and MM2 devices are serially connected (daisy-chained) through RS485. The
following data is set up for the PQMII:
• Read phase current Ia, Ib, and Ic actual values from memory locations 0240h to 0242h
• Read average current from memory location 0244h
• Read neutral current from memory location 0245h
• Read average phase voltage from memory location 0286h to 0287h
The following data is set up for the MM2:
• Read motor status from memory location 0023h
• Read switch input status from memory location 0010h
• Read motor load from memory location 0035h
• Read thermal capacity from memory location 0036h
• Read metered voltage from memory location 0040h
• The START A (command code 0x0005) and STOP (command code 0x0004) commands
using Modbus function 10h: Preset multiple registers.
The memory addresses below are taken from the PQMII and MM2 instruction manuals
available at http://www.GEmultilin.com
. For the PQMII, we have:
For the MM2, we have:
The write command returns data in the response that should not be visible from the
Fieldbus. Also, the write commands should only be sent if the data from the Profibus
master has changed.
If the P485 detects a timeout while talking to the devices (PQMII and/or MM2), it should try
to re-establish communications before it considers the device in subnet is missing
(Number of retries), and then try again after some time (Reconnect time).
The serial communication parameters are set to 19200 bps, with no parity, 1 stop bit, and
8 data bits. The physical interface is set to RS485.
Type Parameter Address Format Read/write
Actual values Phase current Ia 0x0240 F1 Read only
Actual values Phase current Ib 0x0241 F1 Read only
Actual values Phase current Ic 0x0242 F1 Read only
Actual values Average phase current 0x0244 F1 Read only
Actual values Neutral current 0x0245 F1 Read only
Actual values Average phase voltage (2 words) 0x0286 F3 Read only
Type Parameter Address Format Read/write
Actual values Motor status 0x0023 F7 Read only
Actual values Switch input status 0x0010 F100 Read only
Actual values Motor Load 0x0035 F1 Read only
Actual values Thermal Capacity 0x0036 F1 Read only
Actual values Voltage 0x0040 F1 Read only
Commands Command function code 0x1160 F1 Read/write
Commands Command operation code 0x1161 F22 Read/write