Arcnet Bus Termination Link (Lk3) - DAQ IoG User Manual

D A Q E L E C T R O N I C S
This is a 16-pin (8 by 2) link, and is arranged as follows:
Port:
Link Pair 1-2: Port 4 RS-485 (-)
Link Pair 5-6: Port 3 RS-485 (-)
Link Pair 9-10: Port 2 RS-485 (-)
Link Pair 13-14: Port 1 RS-485 (-)
As supplied from the factory, shorting jumpers are installed across all eight link pairs. In
most cases, communication should be satisfactory between the IoG and other connected
RS-485 devices. If, however, the RS-485 devices are chained together, and one or more
of them are already terminated, communication may be impaired. If this is the case, try
removing the shorting jumpers for the RS-485 port in use. If problems still persist,
contact the factory for assistance.

3.4 Arcnet Bus Termination Link (LK3)

The Arcnet Termination Link is used to properly electrically terminate an Arcnet bus,
particularly when two or more IoG's or a mix of IoG's and other Callisto RTU's are
linked together via the Arcnet ports and twisted-pair cabling.
Typically, the node at each end of an Arcnet chain is terminated with a 120 ohm
resistance, and all other nodes within the chain are left unterminated.
2 4 6 8 10 12 14 16
* * * * *
* * * * *
1 3 5 7 9
[ 4 ] [ 3 ] [ 2 ]
- 12 -
* * *
* * *
11 13 15
[ 1 ]
Link Pair 3-4: Port 4 RS-485 (+)
Link Pair 7-8: Port 3 RS-485 (+)
Link Pair 11-12: Port 2 RS-485 (+)
Link Pair 15-16: Port 1 RS-485 (+)
Callisto IoG