Campbell Scientific CR9000X Measurement and Control System - Manual (Page 265)

Section 7. Measurement Instructions
7-41
comparing should either be periodic, or have periods less than the Program
Scan rate. If neither of these conditions are met, the error in the measurement
of the time between edges on the two channels could be up to 1/2 of the Scan
rate.
If using function codes 1 or 2 (return period or frequency of signal), the time
of the last edge prior to the beginning of the scan, and the time of the last edge
of the scan are measured, with a resolution of 40 nanoseconds, and the
difference is divided by the number of edges that occurred within the scan.
This feature eliminates the issues with the resolution of pulse measurements
that are present when using the PulseCount instruction.
See Section 3.4 Pulse Count Measurements for more on the PulseCount
frequency resolution).
I/O 1 - 16 When using the I/O channels with a constant for the AllDoneFlag, the logger
will stay within the instruction until it has results for all measurements
requested. This can result in skipped scans if the input signal frequency is
slow. The resolution is approximately 10 microseconds + 15 microseconds x
the number of results requested.
Pulse channels (P1 thru P12) and I/O channels cannot be
programmed with a single instruction.
Parameter
& Data Type
Enter TIMERIO PARAMETERS
Dest
Var. or Array
Array for results of the measurements.
Pslot
Constant
The slot that the CR9070/CR9071E module is in.
Edges
Constant
There are two Edge parameters, 8 digits each, one digit is for either each of the 16 I/O channels on the
CR9070/CR9071E Module when programmed with a 0 or a 1, or for the 12 pulse channels when
programmed with a 2, 3, 4, or 5. Each digit configures the respective channel to count a transition on the
rising edge (from <1.5V to >3.5V) or on the falling edge (from >3.5V to <1.5V).
Digit Edge
0 Falling, IO channel, I/O 1 to I/O 16
1 Rising, IO channel, I/O 1 to I/O 16
2 Falling, high freq, CR9071E pulse channel only: P1 to P12
3 Rising, high freq, CR9071E pulse channel only: P1 to P12
4 Falling, CR9071E Pulse channels only.
P1 to P8:low level ac; P9-P12:switch closure
5 Rising, CR9071E Pulse channels only.
P1 to P8:low level ac. P9 to P12:switch closure
The first edge parameter is either for I/O channels 16 to 9 or for Pulse channels 12 to 9 (descending
order) depending on the edge code used. The second edge parameter is either for I/O channels 8 to 1 or
for Pulse channels 8 to 1. The digits represent the channels in descending order left to right. For
example, 00000101 in the second edge parameter means channels 1 and 3 count rising edges and
channels 2 and 4-8 are to count falling edges (this could also be specified as 101, the leading zeros do
not need to be entered). Separate instructions are required when programming both I/O and Pulse
channels for TimerIO functions. See PulseCount for description of high freq, low level ac, and switch
closure inputs.
Instruction cannot rep over to another module .
NOTE