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4.3 Jumper Settings

4.3.1 Network Time Out Selection

There are three time-outs associated with the COM9026 operation. These time-outs are referred to as Response Time, Idle Time, and Reconfiguration Time. The ARCNET protocol relies on a token passing scheme. If any node does not receive the token within the Reconfiguration Time, the node will initiate a Network Reconfiguration.

Two jumper blocks have been provided to increase the time-out periods, which allow the network to operate over longer distances than 4 miles.

Time Out Values
JB1 Response
Time		 Idle
Time		 Reconfiguration
Time
78 µs 86 µs 840 ms
285 µs 316 µs 1680 ms
563 µs 624 µs 1680 ms
1130 µs 1237 µs 1680 ms

The default time-out setting for a typical ARCNET network requires no jumpers at JB1.

For proper working of the ARCNET protocol, it is necessary that all nodes connected to the network use the same time-out periods.

CC121 - ARCNET Interface for VMEbus - 30 SEP 1996
Copyright © 1996 Compcontrol, Inc.

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