MKS 250E - How to Use the Multiple Set Point Option; Settings; Selection

How To Use the Multiple Set Point Option Cha
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How To Use the Multiple Set Point Option
The Multiple Set Point Option (MSO) provides up to four front panel set point pots which can be
selected either from the front panel, or remotely. When selected, each set point pot provides a
precision reference for the controller, which will maintain the control pressure (or flow) at the
preset level.
The set point pots are preset with up to four levels which can be selected by using the front panel
selector switch. In the REMOTE position, fully close and a manual signal can be selected, and
an external programmer can select any of the preset levels by activating a digital control line.
Settings
The MSO set point pots are 10-turn precision units with calibrated dials. Each pot covers the full
range of the feedback transducer (0 to 100%). The controllers are calibrated for a precise 10 Volt
full scale and should not need adjustment if a 10 Volt transducer is used. If other full scale
voltage transducers are used, refer to the SPAN adjustment procedure, described in
Front Panel
Controls
, page 24.
The set point controls are your input to the controller. The dial represents the fraction of full
scale range. For example, if the transducer’s full scale pressure is 10 Torr, and a set point is set
for 0.342 (3/42 indicated on the dial), when the set point is selected, the controller will maintain
a pressure of 3.42 Torr in either AUTO or EXT (with no overriding) commands.
Each set point pot should be set to a pressure (or flow) required by the process. The pots can be
adjusted anytime, whether they are ON or OFF.
Selection
When the front panel switch selects a particular set point, all remote select signals are ignored.
In REMOTE, all remote select signals are selected and
it is important that only one set point be
selected at a time.
As normally shipped, the remote set point select lines are wired for negative true; a short-to-
digital ground will select the appropriate set point. When the lines are not shorted to ground, they
are pulled up to +5 V with a 10 K resistor.
If positive true logic is desired, that is, a positive signal (5V) will select the appropriate set point;
then a jumper should be installed near R23 at the rear of the MSO P.C. board.
Note that if
positive true logic is used, all unused set point select lines must be held at digital ground.
As each set point is selected, a light above the set point pot is illuminated.