Response Electronics CL6011B Spécifications télécharger pdf (Page 48)

3Ć28 Theory of Operation: Point Processing

Original Ć June 1990CE4.2:CL6211

3.3.3.3.3 Watchdog Timer

Watchdog timer allows the direct control point to be placed in a specified

backup mode if an update from a console or computer is not received

before the specified time interval and the watchdog timer alarms. It can

only be used with a station type that supports SUP or DDC modes.

3.3.3.4 Functions Common to Primary Control Algorithm and Station

Both the primary control algorithm and the station contain some

functions that are common in theory. These functions are restart values

and set point tracking which are described in the following sections.

3.3.3.4.1 Restart Values

There are several direct control point parameters that have configurable

restart values that may be used if the controller is restarting from a power

failure or a download. In addition to the restart values, the parameters

may also restart from the last value established before a shutdown of the

controller. The parameters which have configurable restart values are the

Set Point (SP), the Implied Valve Position (IVP), the operating mode

(MODE), the bias (BI), and ratio. Indirect Control Point (ICP) reference

values will automatically restart at the last value when a power failure

occurs.

Restart Value Storage

The restart values are retained in non-volatile memory (NVM). Power

fail restart will recall these values from NVM. The restart from last values

are updated in NVM once a minute if the values have changed

significantly. The required amount of change before the NVM value is

updated is 5% of span for set point, bias, IVP and ICP reference values.

The required amount of change before the NVM value is updated is an

absolute change of 0.12 for the ratio value. Mode is updated upon any

change.

Restart After a Power Failure

After a power failure, when restart from last value is specified, the restart

parameters are set to the last value established before the power failure.

When a specific restart value is defined, that value is used as the restart

value after power failure.

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Response Electronics CL6011B Spécifications Page 48