VDH MC2-FC, Руководство пользователя, Страница: 38 / 44

MC2-FC mode FC
Document no.:200064 Version: 1.5
Page 38 of 44
6.2 RS485 connections
The RS485 LAN connection is used to connect the 907.100054 MC3-EM [1Do12,1Rth16] optional
extension module.
The controller can (for the mode FC) work together with other MC2-FC controllers (in mode FC) and
other FC785-PC controllers via the RS485 WAN connection.
With RS485 networks, it is important that the network is terminated electrically at the beginning and
at the end.
The RS485 LAN connection can be terminated electrically on the main circuit board by shifting the
switches Term. LAN 2 and 3 to the right (ON-position). That activates a resistance of 120 ohm
between A and B. By the Term switches. By shifting the switches Term. LAN 1 and 4 to the right (ON-
position), pull-up and pull-down resistors of 500 ohm are activated for signal improvement. Note:
This should only be done at one position in the network.
The RS485 WAN connection can be terminated electrically on the main circuit board by shifting the
switche Term WAN to the right (ON-position). That activates a resistance of 120 ohm between A and
B.
For detailed information about RS485 networks, we refer you to the RS485 standard:
· TIA-485-A, Electrical Characteristics of Generators and Receivers for Use in Balanced Digital
Multipoint Systems (Reaffirmed: December 7, 2012)
· TSB-89-A, Application Guidelines for TIA/EIA-485-A (January 2000)