Operating mode

Selecting the operating modes

There are three operating mode selectable through the man and halt parameter inputs:

Operating mode	man	halt
Automatic	0	0
Manual mode	1	0 or 1
Halt	0	1

Automatic operating mode

In the automatic mode, the function block operates according to the following rules:

If...	Then...
Scan time >	the current X value is transferred to the buffer, and the oldest X value in the buffer is placed on the output Y. If the scan time is more than T_DELAY / 128, resolution is less than 128 causing a systematic error, i.e. some X values are double-stored (see the following Example).
Scan time <	not all X values can be stored in the buffer. In this case the X value is not saved in some cycles. After completion of T_DELAY, output Y may correspondingly remain unchanged in two (or more) consecutive cycles.

Example of automatic mode

In the example the following values are accepted:

Cycle time = 100 ms

T_DELAY = 10 s

tin = T_DELAY / 128 = 78 ms

As the reading time tin is shorter than the cycle time, each X value is transferred to the buffer. On the fourth execution of the function block (after 400 ms) the X value is saved twice rather than once (as 3 x 78 = 312 and 4 x 78 = 390).

Manual mode

In manual mode the manual value YMAN is consistently transferred to the control output Y. The internal buffer is charged with the manual value YMAN. The buffer is marked as charged (READY =1).

Halt mode

The output Y is held at the last calculated value in Halt mode. The output will no longer be changed, but can be overwritten by the user. The internal buffer still continues to operate as in automatic mode.