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17.5
Duplex method
Data circuits support two duplex modes:
•
half duplex
•
full duplex
Half-duplex transmission uses a single transmission path. Two connected devices
can transmit and receive, but not at the same time. If you select half duplex, the
RTS/CTS delay option can be configured (described in section 17.6).
Full-duplex transmission uses two independent transmission paths, one in each
direction, allowing two connected devices to transmit and receive data
simultaneously.
The duplex method can be set for two-port DTUs. The 2606 MainStreet DTU cannot
be set for half duplex.
Procedure 17-4 To set the duplex method
where pp is 1 or 9, and c is A or B
* Default
17.6
RTS/CTS delay
RTS and CTS are control signals used to regulate data flow on half-duplex lines.
When one device wants to send a message to a second device, it sends an RTS. After
receiving the RTS, the second device pauses and then returns a CTS. The pause must
be long enough to clear any messages that might be coming into the second device.
The pause is called the RTS/CTS delay.
For example, using the RTS/CTS delay in multidrop data bridge connections makes
a slave device wait long enough to guarantee that a transmission path has been
established to the master device. An RTS/CTS delay that is too short results in
messages being lost on the line. A delay that is too long decreases response time.
The optimum value depends on your network.
The range for RTS/CTS delay is 0 to 1250 ms in 10-ms increments (the default is
10 ms).
2902 MainStreet Technical Practices
May 2002
90-2906-01
CONFIG — CIRCUIT — <pp-c> ↵ — FUNCTION — I/F_MODE
17 — DNIC and 2B1Q modules
HALF_DPLX/FULL_DPLX*
SK000497
17-5
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