AMX AXCESS CONTROL SYSTEM PROGRAM Instruction Manual page 16

Axcess Basics
2. Then, it starts at the beginning of mainline, the first line of program code after the
DEFINE_PROGRAM header. While executing mainline, the Central Controller processes the
statements in the program, taking whatever actions are defined by the program.
3. At the end of mainline, the Central Controller does some internal processing, then returns to
the top of mainline to start another loop (FIG. 1).
FIG. 1 Mainline execution and internal processing
During this time, the Central Controller operations include:
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After the Central Controller handles these tasks, it executes mainline again:
1. First, the Central Controller scans the wait list for any expired WAITs, then checks the
WAIT_UNTIL list for any WAIT_UNTIL statement whose conditions have become true. If
one of these events has occurred, the Central Controller immediately goes back into the
program and executes the statement or compound statement directly following the WAIT or
WAIT_UNTIL statement.
2. Next, the Central Controller checks to see if any channels activated by the PULSE keyword
need to be turned off. If so, the Central Controller turns them off.
3. Next, the Central Controller handles RS-232 communications. It checks for incoming
characters, executes valid commands typed by the user, and sends out any pending
information.
4. Finally, the Central Controller updates the AXlink bus. During this time, the Central Controller
blinks the green LEDs on all Axcess bus devices, reads pending input changes, and updates all
levels and bargraphs. This action must be done frequently or the AXlink bus will stop
operating, causing the system to stop working.
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Checking the WAIT and WAIT_UNTIL lists
Turning off expired PULSEs
Handling Central Controller RS-232 communications
Updating the AXlink communications bus
Axcess Programming Language