Spectrum 1746sc-CTR4, Owner'S Manual, Page: 46 / 66

46
SLC 500 ™ 50 KHz Counter / Flowmeter Module
The above figure illustrates counting in a clockwise direction.
Using Preset Values
with Extended Mode
The Counter Preset and Counter Limit functions are affected by the
Count Size Configuration Bit 11. The default counter range is ±32K but
may be extended to ±8M.
0
+32K
-32K -8M +8M
Normal Extended
Extended Normal
When operating in the extended range, ±8M, all Counter Preset and
Counter Limit are multiplied by 256. The resolution of the Preset and
Limit values in the standard mode is one count. The resolution in the
extended mode is 256 counts.
Count Size ±32K ±8M Description
Preset Value 1000 256,000 = 1000 x 256
Limit Value 100 2560 = 100 x 256
Using Scaling with
Count and Rate
Outputs:
Count Output:
Counter output scaling is applied using the K & M scale factors. When a
scale factor is applied to the counter the Counter Output Register = (Raw
Count * (M factor /10000) * 1/ K Factor). When a scale factor is being
used the Preset and Limit flags are also scaled.
Rate Output:
Rate output scaling is applied using the R scale factors. When a scale
factor is applied to the module the Rate Output Register = Incoming
frequency / R Factor. When a scale factor is being used the Rate Limit
flag is also scaled.
Example:
As an example if a rate factor of R = 2 is programmed into the module.
The Rate Limit value is set to 10KHz
In this example the Rate Limit Flag would be set when the input
frequency is
≥
20KHz.
Rate Limit Flag = Input Frequency * R factor