Mdsw Mode Switch Function Block - Honeywell HC900 Reference Manual

Function Blocks

MDSW Mode Switch Function Block

MDSW Mode Switch Function Block
Description
The MDSW label stands for Mode Switch.
This block is part of the Loops category.
Function
Digital interface to control loops to select automatic or manual modes and/or local or remote setpoint.
Connects to PID, ON/OFF, CARB, or TPSC mode block input.
Inputs
AUTO = Automatic Output mode (OFF to ON* sets MDRQO to Automatic control mode)
MAN = Manual Output mode (OFF to ON* sets MDRQO to Manual control mode)
LOCAL = Local Setpoint mode (OFF to ON* sets MDRQO to Local Setpoint mode)
REM = Remote Setpoint mode (OFF to ON* sets MDRQO to Remote Setpoint mode)
* for one control cycle
Output
MDRQO (Mode Request Output) = The output of this block must connect to the MDRQI input of a PID,
CARB, TPSC, or ON/OFF function block.
Block properties
Double click on the function block to access the function block properties dialog box.
Example
F igure 53 shows a Function Block Diagram using an MDSW function block.
H
Application: External mode switching of the PID Block - changing a loop to MAN, to AUTO, to LOCAL
SP, or REMOTE SP.
ATTENTION
Mode switching is also provided as an integral part of the Operator Panel, Loop Displays.
The MDSW (Mode Switch) Function Block is used exclusively with the MDRQI (Mode Request Input) of
the PID, ON/OFF, CARB< or TPSC Function Block. Its output provides encoded switch commands to the
PID Block.
208 HC900 Hybrid Control Designer Function Block Reference Guide Revision 11
2/07