Siemens SIMATIC S7-1200

Extended instructions
9.11 Address handling
S7-1200 Programmable controller
550 System Manual, V4.2, 09/2016, A5E02486680-AK
9.11.4
RD_ADDR (Determine the IO addresses from the hardware identifier)
You use the RD_ADDR instruction to get the I/O addresses of a submodule.
Table 9- 234 RD_ADDR instruction
LAD / FBD
SCL
Description
ret_val := RD_ADDR(
laddr:=_word_in_,
PIADDR=>_udint_out_,
PICount=>_uint_out_,
PQADDR=>_udint_out_,
PQCount=>_uint_out_,);
You use the RD_ADDR instruction to get the
I/O addresses of a submodule.
The RD_ADDR instruction determines the length and the start address of the inputs or
outputs based on the hardware identifier of a submodule:
● Use the LADDR parameter to select the input or output module based upon the hardware
identifier.
● The following output parameters are used depending on whether it is an input module or
output module:
– In the case of an input module, the determined values are output at the PIADDR and
PICOUNT parameters.
– In the case of an output module, the determined values are output at the PQADDR
and PQCOUNT parameters.
● The PIADDR and PQADDR parameters each contain the start address of the I/O
addresses of the module.
● The PICOUNT and PQCOUNT parameters each contain the number of bytes of the
inputs or outputs (1 byte for 8 inputs/outputs, 2 bytes for 16 inputs/outputs).