Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 100 / 120

Publication 1757-RM810A-EN-P - May 2002
3-60 Functional Blocks
STEP
Description An SCM block which defines specific output actions.
•
A specified output action usually generates a request to a control device to do something (for example, open a
valve, start a pump, set furnace temperature).
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The source value of each output can be an expression (thereby enabling calculations in each output).
Function Organizes the output expressions of an SCM HANDLER block at a specific stage of the HANDLER's execution thread.
Outputs
•
Up to 16 outputs may be defined per SCM STEP block.
•
The STEP block whose outputs are active is called the Active Step.
Expressions You enter desired output expressions into the Step output configuration form. You compose an output expression to
include a target store destination for a source value and a source expression that generates the value to be stored.
(For example, cm1.pid1.sp := cm2.pid2.op + 50.0.) Source expressions can evaluate to a Boolean value using a
combination of arithmetic and logical operators, to an arithmetic value using arithmetic operators, or may simply
specify any scalar value (Floating Point, Boolean, Enumeration) for comparison in a logical expression or as a value to
be stored to the target store destination. Parameters of other blocks can be referenced as long as the block is already
defined in the system database. Note that :
•
String data types are not supported.
•
Enumerations and Boolean are supported, but values must be entered as integers. For example:
– cm1.flag1.pvfl := 1 (PVFL is turned ON)
Operators and
Functions Table 3.A on page 3-4 lists the expression operators and functions supported by this block.
Parameters ACTIVEFL
ACTVTNTIME
CONFIGCODE
CONFIGDESC
CONFIGSTS
DESC
EXECCODE
EXECDESC
EXECSTS
HANDLER
HIALM
IC.BYPPERM
IC.BYPREQ
IC.CONFIGCODE
IC.CONFIGDESC
IC.CONFIGSTS IC.DESC
IC.EXECCODE
IC.EXECDESC
IC.EXECSTS
IC.EXPR
IC.FL
IC.INVOKFL
IC.OPT
ID
MAXTIME
MAXTIMEFL
MINTIME
NEXTCOMP [1..10]
NEXTHANDLE [1..10]
NEXTNUMBER
NUM NUMOUTPUTS
OP [1..16].CONFIGCODE
OP [1..16].CONFIGDESC
OP [1..16].CONFIGSTS
OP [1..16].DESC
OP [1..16].DSTNCTRLREQ
OP [1..16].EXECCODE
OP [1..16].EXECDESC
OP [1..16].EXECSTS
OP [1..16].SRCEXPR
OP [1..16].STATE
OP [1..16].TYPE
ORDERINCM
PROCESSED
PRODCODEA
SC.BYPPERM SC.BYPREQ
SC.CONFIGCODE
SC.CONFIGDESC
SC.CONFIGSTS
SC.DESC
SC.EXECCODE
SC.EXECDESC
SC.EXECSTS
SC.EXPR
SC.FL
SC.INVOKFL
SC.OPT
STATE
TIME
UPDRESOPT