Rs485 Communication Ports (Eia/Tia-485-A Compatible); 1-Wire Bus - Logic IO RTCU NX-200 Technical Manual

RTCU NX-200 Technical Manual V1.00
Advanced Automotive M2MI/IoT Gateway

RS485 communication ports (EIA/TIA-485-A compatible)

RS485 is a multi-drop network with a maximum of 32 nodes connected simultaneously to the bus.
The RS485 bus contains an RS485+ ( also known as RS485 A, non-inverting) and an RS485- (also known
as RS485 B, inverting) signal as well as a signal ground which must always be connected to the
common signal ground for all nodes connected to the RS485 bus!
The maximum cable length for the RS485 bus is according to the EIA/TIA-485-A standard (max.
1000m @ <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 speeds, it might be necessary
to terminate the transmission line with a 120
terminate it and avoid signal reflections. If the RTCU NX-200 is used as an endpoint node, the
software jumper for both RS485 ports separately can be activated through the user application in
order to terminate the RS485 communication lines with 120Ω.
By default, the RS485 communication lines are not terminated with 120 Ω. Please consult the RTCU
IDE documentation for further information on how to use the software jumpers.
Please note: For best performance, protection and noise immunity shielded cable advised to be
used to connect the device to the RS485 communications bus.
X2: 12 pin COM connector overview.
Pin Name
5 RS485+
6 RS485-
11 SGND

1-Wire bus

The 1-Wire bus is available on the X2 connector. All 1-Wire communication goes through a single
connection, and all 1-Wire devices connected to this connection retrieves its power directly from
the bus (called parasitic power). For this, only two wires are needed – the 1-wire signal and the
ground reference – allowing minimal cable installations.
For 1-Wire ID-Button readers, which include a built-in LED, a dedicated output is available for this
purpose. Please consult the RTCU IDE documentation for further information.
2 Assuming use of a CAT5 twisted pair cable
Logic IO ApS.
Holmboes Allé 14
8700 Horsens
Denmark
1 ohm resistor at each end of the transmission line to
Description
RS485 non-inverting signal (A)
RS485 inverting signal (B)
Signal Ground
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