PROGRAMMING 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 (Pro1&2)to help minimize this effect. The digital filter used is an
“adaptive” filter. That is, the filter coeffecients 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 the final value.
Filter Value Settling Time (99%)
“FILtEr” < > “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 &
OPTIONAL E2-CON PIN
The functions of the remote input “E1-CON” pin (TBA #4) and, if the totalizer
option is installed, the remote input “E2-CON” pin (TBA #8) 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 the 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 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 are 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.
-12-
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