ONICON System-10 MODBUS - Manual (Page 28)

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System-10-MOD Network Interface Installation Guide 05/14 - 0653-10 / 18321
Page 28
SECTION 3.0: NETWORK TROUBLESHOOTING TIPS
3.1 TROUBLESHOOTING
REPORTED PROBLEM POSSIBLE SOLUTIONS
Device will not communicate with the
network controller.
• Is the Receive LED flashing on the network
board? This LED will flash whenever there
is traffic on the network. If the LED is not
flashing, look for an open network cable.
• Is the Transmit LED flashing? The Transmit
LED will only flash when the device is
responding to a poll. 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.)
• The Baud rate setting must match the network
Baud rate. (See section 1.5.1 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
network master 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.