Definition of nominal value of variables in the peripheral input of the process data area
Nominal values of variables are defined at the operator interface and transferred to the peripheral input variables, from where the PLC program can process them further.
The maximum number of variables partly depends on the word addressing length defined in the DP slave, and partly on the length (and therefore the number) of the fault messages in the peripheral input acknowledge area.
Because the variable area is located behind the acknowledge are, the acknowledge area defines the maximum number of possible variables (in addition to the defined word length of the DP slave participant).
The more fault messages have been defined, the fewer variables can be used.
The absolute maximum of variables that can be used is 55.
- DP slave has been defined with 58 words
- no fault messages have been programmed.
Addressing of variables:
All variables are addressed absolutely.
Addressing starts at 0 and ends at a maximum of 54.