14 Introduction—ASC and N2 Bus Networking and Troubleshooting Guide
_
_
N2+
N2-
REF
IN
O UT
P
R
C
5 VDC
1200 ohm
220
ohm
1200 ohm
+
+
EOLWIRE2
EOL
Switch
W1=MM-CVT101
W2=Companion Panel/LTD
W2=MM-CVT101
W4=Companion
Panel/LTD
PRC=Microprocessor
ASC
Figure 5: End-of-line Wiring for MM-CVT101 and
Panel/
LTD Companion
Figure 6 shows an electrical drawing of the end-of-line wiring for the
AHU, VAV, UNT, and LCP controllers.
_
_
N2+
N2-
REF
IN
O U T
P
R
C
5 VDC
100K ohm
18-50K
ohm
100K ohm
+
+
EOLWIRE1
PRC = Microprocessor
ASC
Figure 6: End-of-line Wiring for AHU, VAV, UNT,
and LCP Controllers
The EOL terminations on the MM-CVT101 and Panel/LTD Companion
place a:
●
direct current “bias” on the N2 wires
●
220 ohm resistor from the N2+ to the N2– lines to terminate them
The bias prevents the lines from “floating.” If no communications were
taking place and all the EOL jumpers were set to the Out position, the N2+
and N2– lines would “float.” That is to say, the bus would have no
definite voltage or signal. The receivers would interpret the floating N2
signal as “data,” albeit bad data. To avoid this, and to provide some
impedance termination, one or two end-of-line terminations must be made
on each N2 Bus segment.
Summary of Contents for METASYS ASC
Page 4: ...4 Introduction ASC and N2 Bus Networking and Troubleshooting Guide ...
Page 10: ...10 Introduction ASC and N2 Bus Networking and Troubleshooting Guide ...
Page 30: ...30 Introduction ASC and N2 Bus Networking and Troubleshooting Guide ...
Page 32: ...32 Introduction ASC and N2 Bus Networking and Troubleshooting Guide ...
Page 42: ...42 Introduction ASC and N2 Bus Networking and Troubleshooting Guide ...
