Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 101 / 120

Publication 1757-RM810A-EN-P - May 2002
Functional Blocks 3-61
TRANSITION
Description An SCM block that defines specific input conditions for a Handler.
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Input conditions and conjoining TRANSITION blocks define a distinct process state that must be achieved in order
for the output actions specified by the next STEP block to be performed.
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The input conditions grouped into a TRANSITION block are the condition expressions that direct sequential
execution flow.
Function Defines the distinct process state that must be achieved in order to allow the SCM HANDLER to advance to the
control step (that is, the STEP block) so that it can perform the output actions specified.
Input
Conditions
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A maximum of 10 standard input conditions are supported per SCM TRANSITION block.
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The Invoke TRANSITION block in the MAIN HANDLER of the SCM block provides the Start Conditions for the SCM.
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Logic gates may be AND, OR, NAND, NOR, NOT, XOR, CONNECT, NONE, OFF, or ON.
– XOR must have two inputs.
– CONNECT and NOT have only one input -- the output is the same as the input and the output is the logical
negation of the input, respectively.
– NONE, ON, and OFF have no inputs.
Expressions You enter desired condition expressions into the transition condition configuration form. Condition expressions can
evaluate to a Boolean value using a combination of arithmetic and logical operators (for example, cm1.pid1.sp +
cm2.pid2.op >= 50.0). 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:
– cm2.pid1.mode = 2 (Mode is compared to Cascade)
Operators and
Functions Table 3.A on page 3-4 lists the expression operators and functions supported by this block for reference.
Parameters C [1..10].BYPPERM
C [1..10].BYPREQ
C [1..10].CONFIGCODE
C [1..10].CONFIGDESC
C [1..10].CONFIGSTS
C [1..10].DESC
C [1..10].EXECCODE
C [1..10].EXECDESC
C [1..10].EXECSTS C [1..10].EXPR
C [1..10].FL
C [1..10].GATEASGN
C [1..10].INVOKFL
C1
CONFIGCODE
CONFIGDESC
CONFIGSTS
DESC EXECCODE
EXECDESC
EXECSTS
G [1..4].ALGID
G [1..4].FIRSTCOND
G [1..4].NUMINPTS
G [1..4].SO
HANDLER
HIALM NEXTCOMP
NEXTHANDLE
NUM
NUMCONDS
ORDERINCM
PROCESSED
PRODCODEA
SO
STATE
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