What should you watch out for when configuring an unspecified S7 connection for data communication between an S7-300 and an S7-400?

Configuration Notes:For data communication between an S7-300 station and an S7-400 station, you use S7 Communication with communication blocks FB/SFB12 "BSEND" and "FB/SFB13 "BRCV". In this case, the S7 connection must be configured bilaterally, i.e. in the S7-300 and in the S7-400. Furthermore, the S7-300 station and the S7-400 station are configured in different STEP 7 projects. For this reason