Spectrum Controls 140 EHC 204 00sc - Manual (Page 34)

Counter / Flow Meter Input Module
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Counter Preset:
This output data word is used in conjunction with the Counter Preset enable bit. When this bit
is set, the value in the counter preset word is loaded into the counter. The counter preset can be used
to set the counter to an initial starting value. The bit should be set for at least one I/O scan. The bit
can be held on until the data in the counter data is verified to be equal to the preset value. The
counter will hold the preset value until the counter preset bit is turned off. At this time normal
counter functions will resume. The preset value should always be set less than the Counter limit
value.
When the count size is extended to 16M, the Counters Maximum flag is extended to 16M. The
counter Preset and Limit values are also extended to 16M. This means that the resolution of the
Preset and Limit values are set in blocks of 256 counts (8bits). This allows the preset and limit
values to cover the whole 16M bit range.
Counter Limit:
Note: the User sets The Count Limit and Preset. When the module is in the extended count
mode all limits and preset values are multiplied by 256. If the module has a K factor set the resulting
value is then divided by the K factor.
Rate Limit
This input data register is used in conjunction with the Preset and Count Limit Mode bits.
When the Rate limit value other than 0 is present the data value in this register can be used as an
upper frequency limit and annunciated via the Rate Limit Status Flag. To write the value to
EEPROM the Program EEPROM bit must be toggled from a zero to a one.
M Scale Factor:
In Program Mode the data value in this register is used for scaling. The Scale data can be
stored in EEPROM. To store the scale data in EEPROM valid data must be place into this data
register. When the Program EEPROM bit toggles from a zero to a one, data in the Scale Register
will be written into the modules EEPROM. The M scale factor is used for meter calibration. When
a non-zero Scale Factor value is set the scale calculation is always performed. A value of zero must
be written to the Scale Factor to disable this feature.
The M factor value expressed as a 16 bit unsigned integer divided by 10,000. This value is
multiplied by the counter actual count value, and gives the M factor a range of 0.0001 to 6.5535
Most M factors will be within +- 5% of 1.0000.
K Scale Factor:
The K scale factor is used for flow meter scaling. This allows users to scale the meter output
into more useful units, like gallons. When a non-zero Scale Factor value is set the scale calculation
is always performed. A value of zero must be written to the Scale Factor to disable this feature.
This counter value is divided by the K factor. K factors are be positive numbers.
When a non-zero K factor is programmed into EEPROM, K divides the physical counter value.
Counter Output Value = Actual Counter Value / K.