MAT manual - bumpless transfers

How to do bumpless transfers

Status: this functionality is partially available, as described below.

When using a PID controller, such as the one in the DSP module, it is often useful to be able to switch between manual and automatic modes smoothly.

In the MatPLC, the two directions of switching are set up separately, so we'll cover each in turn.

By way of example, let's say we have the following points:

point type function

Output f32 The output of the PID block, used to control the process.

ManOutput f32 The setting selected manually.

ManMode 1-bit Mode selector: 0=automatic, 1=manual

point	type	function
`Output`	`f32`	The output of the PID block, used to control the process.
`ManOutput`	`f32`	The setting selected manually.
`ManMode`	1-bit	Mode selector: 0=automatic, 1=manual

Manual-to-Automatic transfers

These have to be configured on the PID block. Simply add the following two parameters to the end of the pid block line:

man_out ManOutput
man_mode ManMode

Note: bumpless transfers are not supported when the I coefficient is zero.

Automatic-to-Manual transfers

This depends on which module you use for the manual control, and how manual control is done.

Currently, the hmi_gtk module does not support bumpless automatic-to-manual transfers.

If you're using some other program for the manual control, you can ensure bumpless transfers by copying Output to ManOutput, either just before switching to manual mode or whenever you're in automatic.

If the manual control is done by "up" and "down" buttons, then it's even easier: again, in automatic mode, copy Output to ManOutput; in manual mode, just increment and decrement ManOutput as normal.

$Date: 2006/12/26 13:23:27 $