ONICON System-10 N2 - Manual (Page 19)

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System-10-N2 BTU Meter Installation and Operation Guide 05/14 - 0655-5 / 18322
Page 19
SECTION 3: NETWORK TROUBLESHOOTING TIPS
3.1 TROUBLESHOOTING
Reported Problem Possible Solutions
Device will not communicate with the
network controller. • A unique address is required for each device
on the network. Duplicate addresses will
cause some or all of the devices on the
network to quit working. (See section 1.6.1 of
this manual for details.)
• The RS485 network cable connections are
polarity sensitive and must be connected
the same way on every device. (i.e. + to + and
- to -). (See section 1.4.1 of this manual for
details.)
• Shield drain connections should be daisy
chained in the same manner as the signal
cables for RS485. The shield drain wire
should be left unterminated at the end of
the cable and connected to earth only at the
supervisory controller. Shield wires must not
be connected to the RS485 connector on the
System-10.
• The maximum number of devices allowed on
a RS485 network segment without a repeater
is 32. Adding more than 32 devices to a
single segment may reduce the transceiver
output voltage to a level that is too low to be
distinguished from background noise on the
cable.
• RS485 cable impedance should be matched to
a termination resistor at the end of the cable.
ONICON boards do not have a resistor for
termination. A resistor should only be used if
the display is the last device on the network
cable. (See section 1.5.1 of this manual for
details.)