Oxford Instruments Mercury iTC, Handbook

Page: 124 / 146

Handbook
November 2011 / 59-UMC0071 / Issue 01
Mercury iTC
Page 124
THEORY OF CONTROL LOOPS
Original Instructions
12.2.7 PID tables
Two alternative methods can be used to provide PID parameters to a control loop in the
Mercury iTC cryogenic environment controller:

Manual PID
The PID parameters are entered directly on the
Control Loop Configuration page
(see Section 3.2.9 ). The same parameters are used for the entire temperature range
over which the control loop operates.

Auto PID
The PID parameters are obtained from a PID table (see
Section 3.2.11 ). This method
allows the PID parameters to vary with the controlled temperature.
12.2.7.1 PID table operation
Figure 12-5 shows an example PID table containing two rows. The values shown in this
table are not from a real system.
Figure 12-5 PID table operation
12.2.7.2 Entering a PID table
1 Tap the panel on the Home screen that is to be configured. The Control Loop
Configuration page is displayed.
2 Tap the PID field and set it to Auto .
3 Tap PID Table . The PID Table Editor page is displayed (see Section 3.2.11 ).
4 If a PID table is displayed, tap Save to save the present table (see Section 3.2.16 ).
5 Select the last row in the table and tap the - button. Tap OK in the confirmation field
that appears to delete the row.
6 Continue deleting rows until the table is empty.
7 Tap + to insert a blank row.
8 Tap the first cell in the table and enter the lowest temperature to be controlled. The
next cell in this row is displayed.