OmniCare EVC System
Installation & Commissioning Manual
88 OmniCare issue 1
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A.2 APPROXIMATE CABLE LENGTH
C
ALCULATIONS
To assist with on site fault finding the standard CANBUS
termination resistors have been replaced with 0.1% high stability
resistors from batch 21210 onwards.
This enables approximate cable length to be estimated without
disconnecting the Remote Units from the site cabling.
A.2.1 Distance Between Two Remote Units
Connect an accurate Digital Multimeter between the CANH and
CANL conductors on one unit, and measure the resistance with
both Remote Units connected to the site wiring.
The approximate distance can be estimated using the values
shown in
Table A.2.
Table A.2 — Resistance readings between two Remote Units
NOTE: The following values assume typical characteristics of the
termination resistors, CANBUS driver integrated circuits and cables. The
most accurate method of determining cable length is to use the procedure
described in
Section A.3.
CA U T I O N
Ensure the power is turned off when performing any of the
following measurements.
50m 100m 150m 200m 250m 300m
1.0mm 75.0 75.5 75.9 76.4 76.8 77.2
1.5mm 74.9 75.2 75.5 75.8 76.1 76.4
2.5mm 74.8 75.0 75.15 75.3 75.5 75.7
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