User's Manual

545C Operations Manual

02/10/2012 Prerelease DCN 00001789-A

5.6.4 Programming in Real-Time

Events are programmed via operator commands, one event per command

line. It is a multi-step process. Because of this, each event being entered

will be a fragment until all event definitions are complete. If the event

monitor is allowed to execute a fragment of an event, strange and possibly

adverse actions will occur. Therefore, the operator should stop the event

monitor when adding events and actions to the event table. The event

monitor task can be stopped and started by operator command. The best

way to do this is to use a script file containing the stop ;l,m command, a

command to delete all prior definitions, the desired event definitions, and

a start command.

Some examples are given below, following these, a detailed description of

each event command and action is given.

Example 1: A Scanned Event - Vehicle Tip-Over Detection

Suppose the MCC-545C is wired to detect a vehicle tip-over using the CTS

and DTR signals and a gravity switch that closes if it does not remain mostly

upright. The CTS output is used to enable tip-over detection. The DTR

input is the signal on which tip-over event is detected. Normally open, the

switch prevents DTR from receiving the CTS signal. If CTS is enabled and

the vehicle tips over such that the switch closes, the CTS signal is

presented to DTR.

MCC

-545 RF Modem

CTS

DTR

Gravity

Switch

CTS is set to 5V on power-up, DTR is low if switch is open

DTR will go high when the switch is closed

To make the tip-over detection mechanism function, the CTS signal must

be enabled so that it can be detected at DTR should the switch close. A

good time to enable CTS – set CTS to high – may be when the MCC-545C is

powered up. The command EVENT,RESET,SET,CTS will do this. The event is

RESET. The action is SET,CTS. The “ignition” bit should also be set in the

status word. The bits of the status register are numbered from low order to