8c – Absolute Transducers (Gauge Emu-
lation) with BRT
Absolute transducers with the Barometric Refer-
ence Transducer configuration is shown in figure
9.5 in the Appendix. This pneumatic setup routes
the BRT pressure port to the PCS 400 REFERENCE
port. Table 8.2 shows what happens when each
type of transducer is switched between its native
and emulation mode.
Specifications
Uncertainty: When the active transducer output is
combined with the BRT to derive an emulated
pressure, the uncertainty of the emulated pressure
will increase. The uncertainty should be deter-
mined with the methods described in the ISO docu-
ment ISO Guide to the Expression of Uncertainty
in Measurement.
9 – EXTERNAL ANALOG INPUT
The ANALOG INPUT adds the capability of com-
manding a control pressure output value relative
to a 0 to 10 VDC input signal. After this function is
selected and the instrument is placed in CONTROL
mode the PCS 400 will respond to the voltage ap-
plied to pins 33 (+ VDC) and 34 (– VDC) of the BCD
connector on the rear panel (refer to figure 8.12).
This feature is accessed through the front panel
keypad as follows:
KEY MENU LABEL DISPLAY MESSAGE
[2ND]
[9] CONT CONT PRESS: (NORMAL)?
[2ND]
[3] LIMITS ACTIVE XDUCER SETUP
[+] CONT SETUP CONTROL LIMITS SETUP
[=] CONT MODE CONTROL MODE
[=] NORM NORMAL CONTROL MODE
(or)
[+] RATE CONTROL PRESSURE RATE
[+] EXT CONTROL USING EXTERNAL ANALOG
INPUT
[=] CONT MODE CONTROL MODE
[CE]
[CE] XXX PSI
[=] CONT PRESS (EXT) CONT PRESS: (EXT)
NORM, RATE and EXT cycle when using the [+/–]
keys. Whichever was on the display when leaving
this function will come up first the next time this
menu item is accessed.
At this point in the procedure either enter [=] to
step down to MIN/MAX for setting control limits, or
enter [CE] two times to return to the previous mode
of operation. The sequence just described is used
to place the instrument in readiness to accept
CONTROL input from either the front panel keypad
(NORM), or from the analog input pins of the BCD
connector (EXT). In either event, when in CON-
TROL mode the display will indicate which input
is open.
CONT PRESS: (EXT) 700.000 PSIG
MEASURED: _ 699.989 PSIG [U]
When the PCS 400 is in CONTROL (EXT) mode the
keypad input for setting a control point is disabled.
The analog input (EXT) can change the control
point in 0.025% FS increments. The step changes
are in response to 2.5mv increments of the 0 to 10
VDC input signal. The control point as displayed
on the top line of the front panel will update ap-
proximately once each second. Attempting to set a
control point outside of the MIN or MAX control
limits will cause the control point to reset to the
last acceptible control pressure. An excessively
noisy analog input signal will result in an unstable
control point.
Specifications
Range: 0 to 10 VDC for 0 to full scale control-
led pressure output.
Resolution: 4000 control points at 2.5 mv incre-
ments (0.025% full scale per step).
Regulation: <0.01 mv combined noise and ripple
required.
Control Point Accuracy: ±.05% FS.
Bi-directional Analog Input:
If Analog input is included on a bi-direc-
tional unit (see Option 7) an input of 0.0
volts will correspond to full scale negative
pressure, and 10.0 volts will correspond to
full scale positive pressure.
PCS 400 OPTIONS
www.mensor.com 8-11
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