Connecting two PC adaptors to the same port on a S7-300 PLC

islman1975 said:

We have two PC adaptors, 1 serial, 1 usb and one S7-300 PLC with one MPI port, (and 1 busted profibus port) We want to connect both PC adaptos i.e two PC one running Step 7 and the other running Kepserver for IO simulation and testing purposes. So we need to make a y connector with one male 9-Way Dtype to fit PLC MPI port and then to two female 9_Way Dtype to connect the two PC adaptors. Can someone let me know which pins we need to connect up to get MPI communications and both PC adaptors powered from the PLC MPI port. I've found the following pinouts. Apart from 3,8 what else do I need. Thanks

+ Pin No.+-Signal Name+-Meaning++++++++++++++++++
+ 1 + – + – +
+ 2 + M24V + Chassis 24 V +
+ 3 + RxD/TxD-P + Data line B 9 4 +
+ 4 + RTS + Request To Send +
+ 5 + M5V2 + Data ref.vol.(of station)+
+ 6 + P5V2 + Pwr plus (from station)2 +
+ 7 + P24V + 24 V 1 +
+ 8 + RxD/TxD-N + Data line A +
+ 9 + – + – +

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islman1975 said:

No it works fine I've done it in the past but i lost the adaptor I made up. We've just done it and it works ok have done all severn pins as we were uncertain which ones we would need and left pins 1 and 9 disconnected.

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