GE PACSystems RX7i

Chapter 2. Program Organization
GFK-2950C February 2018 13
Using Parameters with UDFBs
UDFBs support up to 63 inputs and up to 64 outputs.
Each UDFB has a predefined Boolean output parameter, Y0, which the CPU sets to true upon each
invocation of the block. Y0 can be controlled by logic within the block and provides the output status
of the block.
The following table lists the TYPEs, LENGTHs, and parameter-passing mechanisms allowed for UDFB
parameters. For additional information on parameter passing, refer to Parameter Passing
Mechanisms.
Type
Length
Parameter Passing Mechanism
Retentiveness of Instance Data for
Parameters
BOOL
1 to 256
INPUTS: by reference, constant
reference, value, or value result.
(Default: value)
Not Applicable if passed by reference,
since not stored in instance data.
Can be retentive (default) or non-
retentive for value or value result.
OUTPUTS: by result; except Y0,
which is by initial-value result
Retentive (default) or
Non-retentive
BYTE
1 to 1024
INPUTS: by reference, constant
reference, value, or value result.
(Default: value)
Retentive for value or value result.
Not applicable for reference
OUTPUTS: by result
INT, UINT,
and WORD
1 to 512
INPUTS: by reference, constant
reference, value, or value result.
(Default: value)
Retentive for value or value result.
Not applicable for reference
OUTPUTS: by result
DINT, REAL,
and DWORD
1 to 256
INPUTS: by reference, constant
reference, value, or value result.
(Default: value)
Retentive for value or value result.
Not applicable for reference
OUTPUTS: by result
LREAL
1 to 128
INPUTS: by reference, constant
reference, value, or value result.
(Default: value)
Retentive for value or value result.
Not applicable for reference
OUTPUTS: by result
Function
block
(standard or
PACMotion)
1
INPUTS: by reference, constant
reference, (Default: reference)
Not applicable since passed by
reference
OUTPUTS: by result
UDFB
2
1
INPUTS: by reference, constant
reference, friend
Not applicable since passed by
reference
OUTPUTS: not allowed
UDT
1 to 1024
INPUTS: by reference, constant
reference
Not applicable since passed by
reference
OUTPUTS: not allowed
2
A maximum of 16 input parameters can be of type UDFB.