In yours BPN-SAS-743TQ manual for 743TQ backplane I found the following sentence:
#10 - 17. SAS Ports
The SAS ports are used to connect the SAS drive cables. The 8 ports are designated #0 - #7. Each port is also compatible with SATA drives. However, do NOT mix SAS and SATA drives in the same enclosure?
We have not tested and validated mixing the SAS and SATA drives on a backplane. We believe that because SAS and SATA use different protocol, there may be a problem or slow down in performance, and we do not recommend customers to mix the drives