Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 114 / 120

Publication 1757-RM810A-EN-P - May 2002
3-74 Functional Blocks
PICHANNEL (Pulse Input Channel)
PITOTALIZER (Pulse Input Totalizer)
Description Standard interface to channels 0-5 of the Pulse Input IOM function block.
Function The three main functions of channels 0-5 are:
•
Pulse count – both raw count and Engineering Unit converted values
•
Frequency value in Engineering Units
•
Pulse Length measurement in Engineering Units
Inputs If the PIC function block is running, it fetches AVRAW, AV, PV, PL and CHANSTS from its associated PIM function
blocks. If the associated IOM does not exist in the CPM; fail-safe values are used.
Outputs If RESETFL is set, the PIC function block will pass this command to the associated PIM function block.
RESETFL will then be reset regardless of whether the associated IOM exists.
Associated
Block 1757-PIM, Pulse Input Channel with Fast Cutoff, and Pulse Input Totalizer.
Prior to loading, block must be “associated” with 1 channel of corresponding PIM block that interfaces with the
physical pulse input hardware module at execution runtime.
Parameters AV
AVRAW
AVRAWSTS
AVSTS
BADCODE
C1
C2 C3
DEBUG
EDGEDETECT
EXECCOUNT
FETCHMODE
FREEZETIME
FREQPERIOD IOCTYPE
IOMCONN
ORDERINCM
PL
PLSTS
PULSEMODE
PV PVSTS
RESETFL
TIMEBASE
VOLTAGE
Description Periodically adds an input value (P1) to an accumulator value (PV). Sets status flags to indicate when accumulator
value is “near”, “nearer”, “nearest” to the user-specified target value.
Function Typically used to accumulate flows. For situations where flow transmitter may not be precisely calibrated near
zero-flow value, a zero flow cutoff feature is provided such that when P1 is below the cutoff value it clamps to 0 (zero).
Inputs One input (P1) is required:
P1 is the value to be accumulated – input value must be an integer value.
P1 must be fetched from another function block.
Outputs The following outputs are produced:
Accumulated value (PV) and its status (PVSTS), as well as a Boolean flag, PVSTSFL.BAD to indicate to other function
blocks that this block’s PV status is bad.
Flags, indicating if accumulated value has reached user-specified target value or one of the accumulator deviation trip
points (ACCTVFL and ACCDEV.FL [1..4])
Associated
Block 1757-PIM, Pulse Input Channel, and Pulse Input Channel with Fast Cutoff.
Equations Parameter PVEQN may be configured to specify how the block should handle bad input and warm restarts. Specific
handling combinations for a given PVEQN selection are:
Parameters ACCDEV.FL [1..4]
ACCDEV.TP [1..4]
ACCTV
ACCTVFL
C1
C2
CMDATTR COMMAND
CUTOFF.LM
LASTGOOD
OLDAV
ORDERINCM
P1
P1STS PV
PVEQN
PVFORMAT
PVSTS
PVSTSFL.BAD
PVSTSFL.MAN
PVSTSFL.NORM PVSTSFL.UNCER
PVVALSTS
RESETFL
RESETVAL
STARTFL
STATE
STOPFL