Rs485 - Logic IO RTCU MX2 turbo Technical Manual

RTCU MX2 turbo Technical Manual V2.04

RS485

RS485 is available on the X2 connector as serial port 1. The RS485 bus a multi-drop network with a
maximum of 32 units connected simultaneously to the bus. The RS485 bus contains an RS485+
(non-inverting) and an RS485- (inverting) signal as well as a signal ground which must always be
connected to the common signal ground for all units connected to the RS485 bus!
The maximum cable length for the RS485 bus is according to EIA/TIA-485-A standard (max. 1200m
@ <100kbit); this limit is highly influenced by the quality of the cable, signaling rate, noise etc.
At longer cable lengths, noisy environments or high communication speed it might be necessary to
terminate the transmission line with a 120
RS485- at each end of the wires to avoid signal reflections etc.
X2: 12 pin COM connector overview
Pin Name
5 RS485+
6 RS485-
11 SGND
1 Assuming use of a CAT5 twisted pair cable
Logic IO ApS.
Holmboes Allé 14
8700 Horsens
Denmark
ohm resistor between terminal RS485+ and terminal
1
Description
RS485 non-inverting signal (A)
RS485 inverting signal (B)
Signal Ground
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