MODULE #4 - PROGRAM DIGITAL FILTER AND REMOTE INPUT
PROGRAM DIGITAL FILTERING
If the displayed process signal is difficult to read due to small process
variations or noise, increased levels of filtering will help to stabilize the
display. This programming step may be used in conjunction with display
rounding programming
(Pro 1 & 2)
to help minimize this effect. The digital
filter used is an “adaptive” filter. That is, the filter coefficients change
dynamically according to the nature of the input signal. This feature
simultaneously allows the filter to settle quickly for large input changes while
providing a stable display reading for normal process variations. Because of
the adaptive nature of the filter, it cannot be characterized in terms of a time
constant. The following table lists the maximum settling time for a step input
to within 99% of final value.
“FILtEr” < >
Filter Value
Settling Time (99%)
“0” - no digital filtering
1.5 sec.
“1” - normal filtering
2 sec.
“2” - increased filtering
6 sec.
“3” - maximum filtering
13 sec.
PROGRAM FUNCTION OF E1-CON AND E2-CON
The function of the remote input
“E1-CON”
pin
(TBA #4)
and remote input
“E2-CON”
pin
(TBA #9)
are the same. Functions are activated, as described in
the appropriate function, when connected to signal common
(TBA #5).
Whether a function is edge or level activated it must be held low for a minimum
of 20 msec in order for the function to occur. The remote input pins can be used
simultaneously and with any combination of functions. When pins are tied
together and activated, E1-CON function is generally performed first.
“E1-CON” < > “0” - A negative going edge re-zeros
(tares)
the input signal.
Note: The tare buffer can be cleared by “stepping” through
“Pro 2”, using the P button or via serial transmission.
“1” - A negative going edge resets the contents of the totalizer to
zero. Totalization commences regardless of the state of the input.
“2” - A negative going edge resets the contents of the totalizer to
zero and allows totalization as long as the input is low. If the input
goes high, totalization is stopped and the contents are saved. This
acts as a totalization enable control from time T1 to T2.
“3” - A low level allows totalization from the previously saved
contents as long as the input is low. If the input goes high,
totalization is stopped and the contents are saved. This acts as a
totalization enable control from time T1 to T2.
“4” - A low level holds the display
(display hold)
. While this input
is low, the indicator continues to process the input signal and drive
the alarms, totalizer, etc. with the actual signal. The contents of the
totalizer are stored at the same time the input display is held.
Note: If display hold is activated, and input value is requested
via serial, the value on the display will be sent instead of the
actual input value at that time.
“5” - A negative going edge resets both peak and valley buffers.
Note: After P/V is called up, a change will not appear on the
display until the next time the P/V is called up.
“6” - A negative going edge resets only the peak buffer and the
indicator enters a peak reading display mode as long as the input is
low. If the input goes high, peak detection and indication is stopped
and the last peak reading is retained.
“7” - A negative going edge resets only the valley buffer and the
indicator enters a valley reading display mode as long as the input
is low. If the input goes high, valley detection and indication are
stopped and the last valley reading is retained.
“8” - If the alarm option is installed, a negative going edge resets
the latched alarm
(s)
.
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