Siemens SIMATIC S5 Manual page 266

Appendix
Supplement to A.2.2 and A.2.3 (data byte DL n +11):
Note:
The FB supports reading of bytes DRn + 11 (heating and cooling parameters calculated) and
DLn + 15 (minimum jump) in messages 0 to 12 only if main control byte 1, bit 2 = 1.
(Reason: LE is only possible if main control byte 1, bit 2 = 1.)
You may only evaluate the bytes if you have previously read them.
5–62
IP244
C79000–B8576–C861–02