MKS 651C - How to Set the Lead and Gain Parameters

Chapter Six: Remote Operation How To Set the Lead and Gain Parameters
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How To Set the Lead and Gain Parameters
When the 651 unit is configured for PID control, separate lead and gain parameters are
maintained for each pressure set point. Set point A is associated with Lead A and Gain A. Set
point B is associated with Lead B and Gain B, and so forth.
When an analog set point is used with PID control, the lead and gain parameters associated with
any of the pressure set points (set points A through E) may be used. To specify which set point’s
lead and gain parameters to use, apply a TTL low level signal to the I/O connector pin assigned
to the desired set point. Refer to Table 10, page 34, for a description of the pin assignments for
the digital inputs. The TTL low level signal (0 to 0.8 Volts) is “level sensitive” meaning that
once the signal is held low, the 651 unit may take up to 50 milliseconds to recognize the
command. The line must be held low
continuously
for the 651 unit to use the selected
parameters. Once the signal goes high, the instrument will default back to set point A parameters
within 50 milliseconds. The 651 unit will use the lead and gain values associated with set point
A by default.
For example, to apply the lead and gain parameters associated with set point C to the analog set
point, apply a 0 to 0.8 Volt signal to pin 14 (on the I/O connector) for as long as you wish to use
those parameters.
If a set point is configured as a valve position, then
no
lead or gain parameters are associated
with it.
1. To determine which control mode is currently selected, issue the request:
R51
ENTER
The 651 controller will return the following response:
V
value
where
value
is a 0 for Self-Tuning control; a 1 for PID control.
2. If necessary, issue the following command to select PID control:
V1
ENTER
3. Issue the following command to enter a new lead parameter:
X
xvalue
ENTER
where
x
= 1 is the lead parameter for set point A
2 is the lead parameter for set point B
3 is the lead parameter for set point C
4 is the lead parameter for set point D
5 is the lead parameter for set point E
value
= lead value (in seconds)