Instructions

UM-0085-B09 DT80 Range User Manual Page 76
RG
• If a falling edge has occurred since the last reading on a channel, and another falling edge has occurred some
time previously, then the TFF option returns the time interval between the two edges, otherwise it returns zero.
• If a falling edge has occurred since the last reading on a channel, and a rising edge has occurred some time
previously, then the TRF option returns the time interval between the two edges, otherwise it returns zero.
For example:
RA1E 1DS 1DS(TOF,"-edge at") 1DS(TFF,"period")
1DS 0 State
-edge at 15:30:35.015 01/02/2007
period 00:00:00.000
1DS 1 State
-edge at 00:00:00.000 01/01/1989
period 00:00:00.000
1DS 0 State
-edge at 15:30:45.018 01/02/2007
period 00:00:10.003
1DS 1 State
-edge at 00:00:00.000 01/01/1989
period 00:00:00.000
In the above example the A schedule runs when a rising or falling edge on digital input 1 occurs, and reports the time at
which each falling edge occurs, as well as the time between successive falling edges (i.e. the period).
Note: it is not possible to set the schedule to only trigger on falling edges (using RA1-E), because then the state of 1DS would be zero
each time the schedule ran. This would mean that no falling edges (i.e. current value = 0, previous value = 1) would be detected.
Statistical Channel Options
Overview
It is often convenient to sample channels frequently and a return and/or log a statistical summary at longer intervals
(see Statistical Report Schedules (P57)). Statistical channels are sampled during the period between report times (at a
rate governed by the statistical schedule,
RS), and the statistical summary is generated and returned at report time, i.e.
when the regular schedule runs.
Channels that require statistical sampling must include a channel option to indicate the statistical information to generate.
Here’s a summary of the statistical channel options — see also the Statistical (P46) category in the Table 5: DT80
Channel Options (P47) table:
Channel Option
Description
Appended to Units
AV
Average
(Ave)
SD
Standard deviation
(SD)
MX
Maximum
(Max)
MN
Minimum
(Min)
TMX
Time of maximum
(Tmx)
TMN
Time of minimum
(Tmn)
DMX
Date of maximum
(Dmx)
DMN
Date of minimum
(Dmn)
IMX
Instant of maximum (combines DMX and TMX)
(Imx)
IMN
Instant of minimum (combines DMN and TMN)
(Imn)
INT
Integral
(Int)
NUM
Number of samples
(Num)
The statistical option is defined by including it as a channel option in parentheses after the channel type. For example:
RA1M 3TT(AV)(NUM)
3TT 103.7 degC (Ave)
3TT 42 (Num)
3TT 110.2 degC (Ave)
3TT 60 (Num)
In this case you will see the Sample LED flash once per second (which is the default rate for
RS), but data will only be
returned once per minute. These data consist of average of the samples taken since the A schedule last ran, and the
number of samples (which will normally be 60). Note that a tag, e.g. (Ave), is attached to the units to indicate the
statistical function that has been applied.