Honeywell ST700 User Manual page 85

Integration of Inputs
There are three internal registers used for the totalization:
•
Total = The net increment is added every cycle, irrespective of the status.
•
Atotal = The absolute value of the net increment is added every cycle, irrespective of
status.
•
Rtotal = The absolute value of the net increments with status as Bad (rejects) are added
to this register.
The most significant part of Total can be read in the output OUT. OUT_RANGE is used
only for display of the totals by a host. The high and low range values of OUT_RANGE
have no effect on the block.
Types of Integration
The value of OUT can start from zero and go up or it can start from a Setpoint value
(TOTAL_SP) and go down. The Reset option can be automatic, periodic, or on demand.
This is defined by the enumerated parameter INTEG_TYPE:
•
UP_AUTO – It counts up with automatic reset when TOTAL_SP is reached
•
UP_DEM – It counts up with demand reset, and the block resets only when the
operator resets the block.
•
DN_AUTO – The block is reset when the output becomes zero. The integration starts
as SP and increments are subtracted from the SP.
•
DN_DEM – The output is calculated even beyond zero till the block is reset. The
integration starts from SP.
•
PERIODIC – The integration is done for the assigned period (specified in seconds in
CLOCK_PER). After that period, the block is reset automatically.
•
DEMAND – The integration is done (positive or negative depending on the direction
of the flow) until the block is reset.
•
PER&DEM – It is a combination of periodic and demand types. The integration is
carried till the end of the specified period and after that period is automatically reset.
The block can be reset at any time, before the end of periodic data set.
The first four types indicate use as a batch totalizer with a setpoint TOTAL_SP. The count
does not stop at TOTAL_SP going up or zero going down, as it is important to get the
True total of flow. Two outputs, OUT_TRIP and OUT_PTRIP, are associated with the
four types. The next three types indicate that TOTAL_SP and the trip outputs are not used.
The Periodic type (5) disables reset action based on RESET_IN, but has no impact on
OP_CMD_INT.
The internal registers always add the net increments. Counting down is done by setting
OUT to the value of TOTAL_SP minus the most significant part of Total.
Revision 2.0 FOUNDATION Fieldbus ST 700 Pressure Transmitter User's Guide Page 71