Svcreq 23: Read Master Checksum; 1Output Parameter Block For Svcreq 23; 2Example Of Svcreq 23 - GE VersaMax PLC User Manual

11.18 SVCREQ 23: Read Master Checksum

%I0251
CONST
00023
%R0050
220 GFK-1503E
For public disclosure
Use SVCREQ 23 to read the master checksums of the application program and the
configuration. The SVCREQ output is always ON if the function is enabled.
11.18.1 Output Parameter Block for SVCREQ 23
For this function, the output parameter block has a length of 12 words with this format:
The first two items in the output parameter block indicate when the program and
configuration checksums are valid. (Program checksums may not be valid during a Run
Mode Store.)
address
address + 1
address + 2
address + 3
address + 5
address + 6
address + 8
address + 9
address + 10
11.18.2 Example of SVCREQ 23
In the example, when input %I0251 is ON, the master checksum information is placed
into the parameter block at %R0050 and the output coil (%Q0001) is turned on.
SVC_
REQ
FNC
PARM
Master Program Checksum Valid (0 = not valid, 1 = valid)
Master Configuration Checksum Valid (0 = not valid, 1 = valid)
Number of Program Blocks (including _MAIN)
Size of User Program in Bytes (DWORD data type)
Program Additive Checksum
Program CRC Checksum (DWORD data type)
Size of Configuration Data in Bytes
Configuration Additive Checksum
Configuration CRC Checksum (DWORD data type)
%Q0001
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