7
on the RS-232 port. This protocol can be programmed
on the receiver to enable different configurations.
1.5.8 Acknowledgment of the Signal
The System III receiver requires an acknowledgment
signal [ACK] (Hex 06) from the computer software
within 4 seconds for each message sent. Failure to
receive the [ACK] will result in 3 retransmissions of
the signal before indicating a communication failure.
During a communication failure the System III
receiver will cease transmitting except for the heart-
beat. The same thing happens if the receiver receives
a [NAK] (Hex 15). In case of communication failure
with the computer, the System III receiver can store
up to 256 events per line card in the line card inter-
nal memory. Communication is resumed when the
first acknowledgment is received on the heartbeat;
all buffered information is then transmitted.
1.5.9 COM Responses
When the CPM3 sends an event to the computer, it
checks for 3 responses: ACK, NAK or Unknown/No
Response. An ACK tells the CPM3 the computer
automation got the event successfully. A NAK tells
the CPM3 the computer automation got the mes-
sage but didn't understand it. The line card will
attempt to send the messages 25 times. If after 25
attempts it continually gets a NAK from the com-
puter automation, the DRL3 will generate an internal
communication error. After 20 NAKs the CPM3 will
send an internal communication error event to the
printer. Any other response from the computer auto-
mation, including no response will cause the CPM3
to attempt to send the message again, up to 4
times. If after 4 attempts the CPM3 gets no
response or an unknown response, it will assume
nothing is connected and generate an alarm.
1.5.10 Automation Absent
When the computer is not responding to transmis-
sions, the CPM3 will generate a 'SG-Serialx fail' or
'SG-TCP/IPx Fail' trouble. When a trouble occurs, the
CPM3 will continue to attempt to send a heartbeat
signal to the computer until it gets a response. The
System III receiver will make 4 attempts, then wait for
the next heartbeat period before making another 4
attempts. The typical heartbeat interval is 30 seconds.
This signal is used to supervise the communication
between the receiver and computer automation. It is
sent to the computer automation every 30 seconds
and is programmable from the receiver. The com-
puter automation should acknowledge this signal
with an [ACK]. The CPM3 can be programmed to
send a heartbeat signal to the computer automation
once every 01-99 seconds to test the connection
between the CPM3 and the computer automation
(30 seconds is recommended). If a heartbeat fails to
get a response from the computer automation, the
CPM3 will immediately transmit the heartbeat again,
up to 4 attempts. The SG-System III, by default, will
output the automation signals via TCP/IP. If TCP/IP
fails it will switch to the Serial Automation output.
If the serial output fails, the CPM3 will switch to
manual mode, all signals will be displayed on the
LCD and will require a manual acknowledgement. To
re-establish connection with the TCP/IP a reset SG
fallback command must be generated from the Con-
sole software. If the line card buffers are full, the line
cards will stop answering calls.
1.5.11 System III SIA Internal Status Output
Refer to “CPM3 Internal Status Messages” on
page 35.
Supervisory Heartbeat Signal Protocol (1)
00000
s
@
[DC4]
100000sssssssssss@ssss[DC4]
Receiver number (Real programmed number.
Never virtual).
Space Character.
Supervisory Signal.
Terminator, 14 Hex
0
RR
LLL
0000
NYYZZ
[DC4]
0RRLLL[#0000|NYYZZZZ]
Protocol ID
Receiver number of the CPM3
Line card number, 000 signifies a
CPM3 Event.
System III account.
SIA Event
Terminator, 14 Hex
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