ABB 266 Operating Instruction page 67

If the input option is Accum:
A counter input normally comes from a Pulse Input block OUT_ACCUM. It can also be connected to the output of another integrator
block. The OUT_ACCUM of the Pulse Input block represents a continuous accumulation of pulses from the flow transducer, while the
output OUT of an Integrator represents an integration or accumulation of analog inputs.
The Integrator block should determine the number of additional counts from the counter input readings since the last execution.
As the output ACCUM_OUT of the Pulse Input block wraps up when the counting reaches 999,999 and does not increment or
decrement by more than 499,999 per cycle, the difference in counts is determined as follows:
– If the difference between the reading in one cycle and the reading in the preceding cycle is less than 500,000 or greater than
(-500,000), the difference should be taken as the variation.
– If the difference between the reading in one cycle and the reading in the preceding cycle is greater than or equal to (+500,000), add
(-1,000,000) and use the result as the variation.
– If the difference between the reading in one cycle and the reading in the preceding cycle is more negative than or equal to
(-500,000), add (+1,000,000) and use the result as the variation.
If the output OUT of another integrator block is used, that block should be programmed to obey the rules listed above.
The variation of each input should be multiplied by the value, in engineering units, of each pulse given by PULSE_VAL1 or PULSE_
VAL2, as appropriate. The result is the increment in engineering units of, for example, mass, volume or energy per block execution
(please see diagram below).
Net Flow
In order to discern between forward and reverse flows, the Integrator block considers a negative sign as an indication of reverse flow.
Some flowmeters already indicate forward and reverse flows by adding a sign to the measurement value. Others use a separate
binary signal. This signal can be connected to the inputs REV_FLOW1 and REV_FLOW2, where True should invert the signal of the
corresponding input. The net flow is obtained by adding the two increments. The net increment should have a positive or negative
signal to indicate the net flow direction. In order to integrate the difference between the inflow and outflow of a tank, for example, the
second one can be assigned to be negative.
The net flow direction to be considered in the totalization is defined in INTEG_OPTS. The following options are available:
FORWARD = only positive flows (after application of REV_FLOWi ) are totalized. The negative values should be treated as zero.
FORWARD is selected when the bit corresponding to Forward is set to true.
REVERSE = only negative flows are totalized. The positive values should be treated as zero. The option bit Reverse should be set to true
TOTAL = both positive and negative values should be totalized. Both option bits Forward and Reverse should be set to true or to false.
Integration of Inputs:
There are three internal registers used for the totalization:
Total = The net increment is added every cycle, regardless of status.
Atotal = The absolute value of the net increment is added every cycle, regardless of status.
Rtotal = The absolute value of the net increments with bad status (rejects) are added to this register.
These internal registers may have greater precision than the standard floating point value. The value of Rtotal requires the same
precision as Atotal in order to be able to accumulate floating point fractions so that they are not lost as arithmetic underflow.
The value of a register that corresponds to standard floating point is called the most significant part of the register. The most significant
part of Total can be read in the output OUT, and of Rtotal in RTOTAL. OUT_RANGE is used only for display of the totals by a host. The
2600T Series Pressure transmitters | OI/266/FF/ADD-EN Rev. B 67