heartbeat
heartbeat — creates a point of type
heartbeat.
Synopsis
(heartbeat enable_flag name cycle_millisecs expression)
Parameters
- enable_flag
- The initial value of enabled status of the
point. t will
cause the point to be initially enabled. f
will cause the point to be initially disabled. (see enable
and disable
commands).
- name
- The
name of the heartbeat point.
- cycle_millisecs
- The cycle (or heartbeat) time in
milliseconds associated with the group, upon which automatic
reading or writing is performed. Typically, points are read
or written in groups, and the individual cycle time for each
point is set to 0.
- expression
- (optional parameter) A string defining the
expression to be evaluated on each cycle. The expression
consists of one or more commands as defined in this section.
If no expression is supplied, then the default behavior is to
increment a variable in the Cascade DataHub of the same name as the
heartbeat.
Description
This command creates a point of type heartbeat, used to
trigger processing on a timed-interval basis. It is normally executed
from the configuration file.
Example
(heartbeat t drv_alive 500)
(heartbeat t still_alive 500 "write trigger 1")
