Cascade Driver for Hilscher Fieldbus CIF Cards: Version 4.1
Prev |  | Next

# 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.

## Returns

`OK` or `(error).`

## 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")

Prev | Home | Next
group | Up | include

Copyright 1995-2002 by Cogent Real-Time Systems, Inc.