Alicat P Series Pressure Gauge - Manual (Page 43)

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The output signal is lower than the reading at the display.
This can occur if the output signal is measured some distance from the gauge/
controller as voltage drops in the wires increase with distance. Using heavier
gauge wires, especially in the ground wire, can reduce this effect.
My controller oscillates wildly and/or exhibits very different reactions to the set-
point than I expect.
Conditions considerably different than those at which the device was originally
set up can necessitate a re-tuning of the PID loop. See pages 27 and 28 for
more information on PID tuning.
RS-232 / RS-485 Serial Communications is not responding.
Check that your gauge is powered and connected properly. Be sure that the
port on the computer to which the gauge is connected is active. Confirm that
the port settings are correct per the RS-232 / RS-485 instructions in this manual
(Check the RS-232 / RS-485 communications select screen for current gauge
readings). Close HyperTerminal® and reopen it. Reboot your PC.
See pages 11, 12 and 33 for more information on RS-232 / RS-485 signals and
communications.
Slower response than specified.
P-Series Gauges and PC-Series Controllers feature an RS-232 / RS-485
programmable Geometric Running Average (GRA). Depending on the full scale
range of the gauge, it may have the GRA set to enhance the stability/readability
of the display, which would result in slower perceived response time. Please see
“Pressure Averaging” on page 19.
Jumps to zero at low pressure.
P-Series Gauges and PC-Series Controllers feature an RS-232 / RS-485
programmable zero deadband. The factory setting is usually 0.5% of full scale.
This can be adjusted between NONE and 3.2% of full scale. See page 19.