Optelecom 9522A Installation And Operation Manual page 29

 Set the RS232 Anti-Stream Enable/Timeout. Set S2-1, S2-2, and S2-3 to either disable or select the
RS232 anti-streaming timeout. Refer to the Anti-stream Timeout section in System Architecture and to
Table 4.
Table 4 — Switch S2, Timeout/Streaming Set Up
1 2
Down Down
Up Down
Down Up
Up Up
Down Down
Up Down
Down Up
Up Up
 Set the Optical Anti-Streaming Option. This function is set by S2-4. Refer to the Optical Anti-Streaming
section of System Architecture and Table 5.
Table 5 — Switch S2, Streaming Set Up
1 2 3
 Set the Priority Timeout Value as explained in Priority Timeout Section of System Architecture, set S1-5.
Refer to Table 6. To help in the selection, consider the following:
1. The Priority Select function is not used when operating in Daisy Chain Mode.
2. The purpose of the Priority Select timeout is to keep the modem output from switching from one
receiver to the other within a data message, between bits, rather than only at the beginning of a
message. To prevent this, select a timeout equal to one whole byte, say 10 bits, at the operating data
rate. For example, at 4800 bps one bit equals 208 microseconds. Ten times 208 microseconds equals
2080 microseconds or about 2.1 milliseconds. Select the 2.22 ms timeout. For data rates above this,
also select the 2.22 ms. timeout. For slower data rates, select the 8.88 ms timeout.
3. WARNING: If one of the rings in a fault tolerant ring is broken, a modem on the ring may only be
able to receive an important signal from one direction. In this case, unless a time period greater than
the priority select timeout elapses before the next transmission occurs, the priority select circuit will
not be able to react in time and the first portion of the message could be lost. Therefore, the priority
select timeout limits the speed at which a terminal may respond to a poll and limits the polling rate.
Select the timeout accordingly.
Table 6 — Switch S2, Priority Select Set Up
1 2 3
3 4 5 6
Down
Down
Down
Down
Up
Up
Up
Up
4 5 6
Down
Up
4 5 6
Down
Up
7 8 Function
RS232 Anti-Stream Disabled
RS232 Anti-Stream Enabled – 64 Seconds
RS232 Anti-Stream Enabled – 32 Seconds
RS232 Anti-Stream Enabled – 16 Seconds
RS232 Anti-Stream Enabled – 8 Seconds
RS232 Anti-Stream Enabled – 4 Seconds
RS232 Anti-Stream Enabled – 2 Seconds
RS232 Anti-Stream Enabled – 1 Second
7 8 Function
Optical Anti-Stream Disabled (RS232 Only)
Optical Anti-Stream Enabled (RS422, RS485 Only)
7 8 Function
Priority Select Timeout 2.22 ms.
Priority Select Timeout 8.88 ms.
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