GE Industrial Solutions EntelliGuard TU Trip Units - Manual (Page 64)

EntelliGuard TU Trip Units: UL/ANSI Models DEH-4567B
Serial Communication
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In this example, a USB-to-serial port has been configured
as COM1, and would be the port you would use to
communicate with the trip unit.
Step 2: Configure the Communication Settings on the
Trip Unit: Baud Rate, Parity, Stop Bits, Modbus Slave
Address/ID
Step 3: Supply 24VDC to the Trip Unit, and Connect the
Trip Unit to the Computer
You can connect a test kit between the computer and the
15 pin front panel port, or you can wire to the RS-485
terminals on the circuit breaker secondary disconnect.
Step 4: Configure the Master’s Communication
Parameters
• Modbus Address matches the trip unit
• Baud Rate matches trip unit
• Parity matches trip unit
• Stop bits equals trip unit
• Modbus requests are made using “Modbus RTU Serial”
Step 5: Attempt to Communicate with the Device
The registers listed below will return easily identified values
that can be confirmed by reading the same setting from
the device via LCD. This gives you instant feedback on
whether the system is properly configured or not.
a. Read Modbus address.
• Register Address: 211. If using Modicon addressing,
add 40001 for an address of 40212.
• Function Code: 03
• Expected Value: matches the Modbus address of
the trip unit
b. Trip the breaker.
• Register Address: 108. If using Modicon addressing,
add 1 for an address of 109.
• Function Code: 05 ON (send 0x00FF)
• Expected Value: a closed breaker will trip.
c. Read voltage on Phase A. To generate voltage data,
engage the “Phase Current” feature on the GTUTK20
digital test kit.
• Register Address: 18. If using Modicon addressing,
add 30001 for an address of 30019.
• Function Code: 04
• Expected Value: matches the voltage metering
value displayed for phase A.