937B Controller Instruction Manual
pg. 26
9. PID Recipe
The 937B does not have pressure control capabilities. This function is disabled in 937B as there
is no MFC or pressure control valve capability. It is available in the 946 Vacuum System
Controller.
10. Ratio Recipe
This function is disabled in 937B as there is no MFC capability. It is available in 946 Vacuum
System Controller. This function for direct valve control is disabled in the 937B. It is available in
946 Vacuum System Controller
.
This function is disabled in 937B as there is no MFC or direct
valve control capability. It is available in the 946 Vacuum System Controller
11. Screen Saver
Screen saver turns OFF the front panel display. The front panel display can be re-activated by
pressing any button on the front panel. The value of the screen saver is the time in minutes (1 to
254) for time of inactivity after which the screen saver is activated. To disable this function, set
the value to zero. Remote operations are not affected by the Screen Saver setting. Default setting
is OFF (0).
12. Combination Setup
Two analog output combination channels are available on the 937B. Up to 3 vacuum pressure
sensors can be assigned to each combination channel. Refer to section 8.4 for a more detailed
discussion of the settings for the combination channels.
13. Set DAC Parameter
Scaling of the Log/Linear analog output for each individual channel, as well as the combination
analog output can be changed by adjusting the DAC parameter. To view or modify the DAC
parameter, press SYSTEM SETUP and move the cursor to Set DAC Parameter. Select Edit and
press ENTER. The DAC parameters used in scaling the logarithmic/linear analog output are
displayed as shown in Figure 6-5.
Both values for slope A and offset B must be selected when a logarithmic linear equation is used.
The slope A is the voltage per decade, and the offset B is the voltage when the pressure is 1 Torr.
The valid range for A is from 0.5 to 5, while the valid range for B is from
–20 to +20 V. The default
settings are 0.6 and 7.2 for A and B, respectively, which provides for a 0.6 to 9.6 Volt output over
the maximum pressure range covered by the Controller. If a single channel module is present in
(HC or CC), only one equation is displayed (Channel A example in Figure 6.6).
Linearized analog output can be used when high analog output resolution is required over a
narrow pressure range. When a linear equation is used, the parameter B is always set to zero as
it indicates zero voltage output at high vacuum. The A value can be calculated using the equation:
A =
10
𝑃
𝑚𝑎𝑥
Here, P
max
is the maximum pressure when analog output voltage is 10 V. For a Capacitance
Manometer, the full range of the Manometer is normally selected for P
max
. For example, if a 1000
Torr manometer is connected (P
max
=1000), 1×10
-2
should be selected for A. For other types of
gauges (such as CC, HC, PR, CP), linear analog output can be used to magnify the analog out
over a special range. For example, if the pressure range from 10 to 10
-1
Torr needs higher
resolution, (P
max
=10), a value of 1 can be selected for A which results in 10 V analog output at 10
Torr.