Eaton PXR10 - 9 Modbus RTU - Integrated Modbus Port Specification

9 Modbus RTU – integrated Modbus port specification
PXR Electronic trip unit 01/21 MN012005EN www.eaton.com 49
9 Modbus RTU – integrated Modbus port specification
The internal Modbus communication module is an optional accessory for
digital NZM circuit breakers with PXR technology.
This module enables the communication between the release and a
Modbus RTU fieldbus.
If supplied with a voltage of 24 V DC, the trip unit can communicate as a
slave device via the Modbus A, Modbus B and Modbus COM contacts.
The Modbus cable has to comply with the following specifications:
• at least one pair of twisted wires
(signal cable Modbus A, Modbus B)
• at least one ground wire (Modbus COM)
• HF-compatible shielding (including HF-compatible grounding)
• compatibility with the respective environmental conditions
(temperature, humidity, chemical resistance, etc.)
• The cross section of the wire is as follows:
The wiring is done as follows:
Figure 13: Wiring
a Modbus RTU input cable
b Modbus RTU output cable
c Bus termination resistor (for the final node)
d Modbus RTU-compatible cable: triple wire; two twisted signal wires; one shielded COM wire
e HF-compatible functional grounding
a = 6 mm (a = 0.24 ″)
0.15 - 0.5 mm
2
AWG26 - AWG20
0.20 - 0.5 mm
2
AWG26 - AWG20
0.25- 0.5 mm
2
AWG26 - AWG21
2.0 x 0.4 mm
a
120R
A
B
COM
A
B
COM
A
B
COM
①
②
③
④
⑤

③