Siemens SIMATIC S5 Manual page 109

Data Exchange with the Central Controller
Byte 21 Main control byte 6
If mixed operation has been selected, the IP cannot execute the following functions simultaneously:
– special function
– heating current monitoring
– Pt 100 operation
– processing of channels 13 and 14
– comparator
– pure hot channel control and
– cascaded control.
4–42
IP244
C79000–B8576–C860–02