ACL CSC400 User Manual

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Appendix B - Modbus/RS-485 Cabling Technical Details
Additional Modbus documentation is available at
www.modbus.org:
RS-485 Signal Naming Conventions
The RS485 signal naming convention used in this document and by many RS485 transceiver vendors is reversed from what the
EIA/TIA-485 specification states:
CSC400
Modbus/RS485
Documentation
EIA/TIA-485
Naming
Convention
Modbus
Specification
Name
Description
A (“Data A +”)
B
D1
Non-Inverting, Transceiver Terminal 1, V1 voltage (V1 > V0
for binary 1 (OFF) state
B (“Data B –“)
A
D0
Inverting, Transceiver Terminal 0, V0 voltage (V0 > V1 for
binary 0 (ON) state
Isolated GND (or
common GND)
C
Common
Signal and Optional Power Supply common ground
Half-Duplex vs Full-Duplex
Half-duplex communication allows only one device to communicate over the two RS-485 wires (one differential pair) at a
time. Full-duplex communication adds another pair of wires to allow bi-directional communication between a PC/PLC master
and a slave unit simultaneously.
The CSC400 provides a three pin terminal for half-duplex communication between the CSC400 and a host master Modbus
device.
Cable Types
Master Used
Cable Type To Use For
Testing
Notes
PC
USB to RS485 cable
RS485 cable should have stripped wires for
connecting to terminal blocks on the CSC400
Controller
PLC – Programmable Logic
Controller (eg: SCADAPack,
ROC800 series)
CAT5E
Use a matched twisted pair for RS485A+/B-
Eg: Blue for RS485A+
Blue with white stripe for RS485B-
Allowable Pairings of CAT5E Cable
Signal
CAT5E Cable Wire Color Twisted Pairs
Notes
RS485A + or Data +
Blue
RS485B - or Data -
Blue with white stripe
Refer to the document "CSC400_Modbus_Installation_Manual.pdf" for additional details
on additional Modbus registers, programming, testing, and troubleshooting.

ACL CSC400 Specifications

General

Brand	ACL
Model	CSC400
Category	Controller
Language	English