Using scaled values, Changing values in the manual mode – Rockwell Automation 1747-PT1, D1747NP002 Hand-Held Terminal User Manual

Page 359

Chapter 26
PID Instruction

26–15

The second display shows the status bits discussed in the last section:

ZOOM on PID –(PID)– 2/2 2.0.0.0.1
NAME: PROP INT DERIV MODE: MANUAL
LOOP UPDATE: 50 [x10ms]
SET PT RANGE: –100 1000
EN DN PV SP LL UL DB TF SC OL CM AM TM
0 0 0 0 0 0 0 0 0 1 1 1 1
PRG
PREV PG

Using Scaled Values

If you are using scaled values with the PID instruction, note that the HHT
Zoom display in the monitor mode indicates the unscaled value of the
Process Variable PV (PROCESS in the figures above). To display the
process variable in its scaled form, view the control block of the PID
instruction (shown on page 26–8). Word 14 contains the scaled value of the
Process Variable PV. To view the scaled error, view the control block of the
PID instruction. Word 15 contains the scaled error.

Changing Values in the Manual Mode

In the manual mode the Zoom display allows you to change only the
OUTPUT % value:

ZOOM on PID –(PID)– 1/2 2.0.0.0.1
NAME: PROP INT DERIV MODE: MANUAL
PROCESS: 0 SETPOINT: 500
OUTPUT: 95%
MIN OUT: 5% MAX OUT: 95%

ENTER OUTPUT PCT: 95 PRG
NEXT PG AUTO

Only the Output %

can be changed at

this display.

You can change the Setpoint, Deadband, Gain, Reset, Rate, Output min %,
and Output max % parameters by writing to the appropriate word within the
control block of the PID. The control block is shown on page 26–9.