QUESTION:
Why do I receive information on the status of 27 configured blocks
at maximum, when parametrizing the partial list SZL 0E91 of system
function SFC51?
ANSWER:
Partial list 0E91 of the system function SFC51 does only apply for
S7-400.
With parametrization of partial list SZL 0E91 of the system
function SFC51 you receive status information of all
configured blocks - independently of whether or not they are
plugged to the rack.
For each configured block, 8 words or 16 bytes must be reserved -
independently of whether or not these are plugged in the rack.
Below table describes the structure of the data set of SZL
partial list 0E91.
| Name |
Length |
Meaning |
| adr1 |
1 Word |
In case of central
setup:
number of the block of the physical address
In case of distributed setup with
PROFIBUS DP:
ID of DP master system, stations number
In
case of distributed setup with PROFINET IO:
the last two digits of the ID of the PROFINET IO system, stations
number |
| adr2 |
1 Word |
In case of central and
distributed setup with PROFIBUS DP:
number of the slot and of the submodule slot
In case of distributed setup with PROFINET IO:
number of interface |
| logadr |
1 Word |
First assigned logical I/O address (basic
address) |
| solltyp |
1 Word |
PROFINET IO: setpoint type,
reserved otherwise |
| isttyp |
1 Word |
PROFINET IO: actual type, reserved
otherwise |
| alarm |
1 Word |
Reserved |
| eastat |
1 Word |
I/O status |
| ber_bgbr |
1 Word |
Area ID / Width of block |
Tab. 1: Structure of a Data
Set of the Partial List with SZL ID:= W#16#xy91
The general limitation of SFC51 is ca. 440 Byte.
For a configuration of 27 blocks you therefore receive an overall
size of 27 * 16 bytes = 432 bytes. Hence details of block status of
at maximum 27 blocks is possible. Further blocks cannot be
displayed.
Further information on the structure of the data set of the
partial list SZL you also find in the online help of STEP 7 in
"SZL-ID W#16#xy91 - Block status information".
Key Words:
SZL-ID, SFC51 "RDSYSST" (read system status)
| 
german
