Section 1
SUPERVISOR PROTOCOL
2
Supervisor will not start, stop, load or unload unless a message commands the action.
If the sequence parameter is set to HOURS or COM ID# then the broadcast mode is
enabled. In this mode the machines send the net status message periodically.
Approximately once a second, all machines that are on line will send a net status message.
In this manner, each machine knows the status of every other machine. Sequencing deci-
sions are made individually by each machine based on the status of all on line machines in
the system. Collisions on the serial channel
are avoided by a time slice scheme (See section on Time Slice).
BROADCAST MODE OFFERS SEVERAL ADVANTAGES:
1. Because there is no master, the number of messages are cut in half (decreasing
response time). In master/slave mode the master must send a message to request sta-
tus and the machine must send a message back. In broadcast mode, each machine
sends it’s status approximatley once a second.
2. When a machine goes off line or on line there is no need to poll for a new master.
3. Individual machines may be taken off line or put on line with no effect on communications.
This is handy for maintenance or when a machine is to be controlled manually.When the
machine is stopped it still sends net status messages so other machines or a monitor can
display it’s status. When the machine is DISABLED it will not send net status messages
but will respond to status and parameter change messages.
4. Because decisions are made locally, the response of the system is very good, less than
one second for trimming, loading and unloading. One second plus starting time for a
machine to start.
5. There are no extra communications for monitoring. Since each machine sends it’s status
every second, the monitor does not need to send messages. However, the monitor may
send messages to get other status, change parameters or issue run commands (for
example a machine may be stopped from the monitor).
6. The monitor does not need to be continuously connected. A monitor may be connected
or disconnected at any time.
MESSAGE FORMAT
All messages will have the following format.
@ Start of text (2)
## Two character com number
m One character message type
d Zero to several data characters (values separated by comma’s)
xx Two character check sum
CR Carriage return (13)
LF Line feed (10)
For the following examples the STX, CR and LF will not be shown.
Message transmission format is 8-bit, 1-stop bit, no parity.
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