Product manual

CAD Interface Installation
68 025-9158L
CAD Command Station Relay Control
When the CAD wants to energize a relay at one of the stations, the following exchange
takes place. Note that the status of the relays is NOT returned.
tm Transmitted from CAD to M26 Response from M26 to CAD
t0 Station Relay Control 01, HL45,LL 00>
t1 <LLACK 00
t2 <High Level ACK HL 45,LL FF
t3 LLACK FF>
Text - A Special Case
The sequence of commands CAD must use for sending text is a set of three exchanges:
• Defining the Text Channel (multiple Model 6s may receive the same text).
• One or more Send Text messages.
• End Text message.
Only one text channel may be open at a time and must be defined as channel 0. The
number of stations which may be included in one text channel using the Define Text
Channel command is limited to 16. If multiple copies of text have been specified for one
or more of the stations, the additional copies will be printed following the receipt of the
End Text command.
Each CAD command must wait for the prior high level ACK before being sent to the
Model 26. In a system with no communication errors, the high level ACK will vary in
response time from 100 milliseconds to 2 seconds in some RF systems. Communication
errors and system retries could take up to 15 seconds for the ACK/NAK to be received.
Since the entire text sequence could take many seconds to complete, certain operations
are restricted while text is being broadcast. Any CAD command is allowed to be inserted
in the middle of a text sequence. When a PA channel has been opened to a Model 26, text
should not be transmitted until the PA channel is closed. While a text channel is open, the
automated polling sequence is suspended until the End Text message (in the wire line
communication mode, system polling is continuous). The text channel should be closed
as soon as possible so the polling sequence can continue.
The All Stations number can be used to define the station address so text messages will
be sent to all Model 6s. With all station text, no polling of Model 6s is used to verify the
Send Text or End Text commands.