ACC HDLC-NRM (SDLC) User's Guide

Protocol Specific Configuration
Protocol Configuration Values
Chapter 454
BCT - Broadcast terminal (Extension feature)
Set to make a terminal the broadcast terminal for the port. A single
broadcast terminal may be configured on either a primary or secondary
port. A broadcast terminal’s address should be set to 0xFF.
The broadcast facility is an extension feature of the HDLC-NRM (SDLC)
basic procedures as described in ISO 4335. The broadcast facility allows
the primary control station to send messages without acknowledgment to
all secondary addresses on a line (if these are capable of receiving such
messages).
For a line configured for secondary operation, a secondary broadcast
terminal may be configured to allow the reception of any broadcast
messages sent by the primary control station. In this implementation,
the secondary broadcast terminal only will receive broadcasts, and not
any of the other secondary stations.
For operation with the broadcast facility, a terminal ZLU should be
configured with the all stations address “11111111”, (0xFF) in addition
to the real terminals. Messages to be broadcast should be sent to this
virtual terminal ZLU by an application program. On the secondary line,
all broadcast messages will be received by the secondary broadcast
terminal.
The virtual broadcast terminal is distinguished by this BCT option
setting which will change the way in which this terminal will be handled
by the protocol as follows:
•No RPC
•No SNRM
• No polling
A broadcast message will be sent as an unnumbered information (UI)
command with P bit set to zero (0). No response is expected to the
broadcast message from any secondary station.
RTS - Controlled RTS
This option flag may be set to enable the control of the RTS signal as
frames are transmitted. This option must be set the same for all
terminals on the port.
If set to zero, the RTS control signal is left permanently ON after the
port is enabled.