we have one S7-300 and one SCADA. this system communicate with MPI/PPI cable. cable lenght about 10 m. we want to increase cable lenght.how is possible?
DP: I have to use MPI/PPI protocol.
*If you mean to communicate with PC adapter set, transmission is RS232 from PC to PC adapter box (I have worked with a serial printer and about 30m cable with no problems)
*If you have connected Scada and S7-300 via MPI,
MPI uses standard RS485, the same as profibus, so you should be able to reach up to 1000m distance at 187,5KBaud.
Hi,
I guess you mean with 'MPI/PPI cable' not the converter from RS232 to RS485. If so, you need just a Profibus cable to connect two Profibus or MPI devices to each other(max. length is 1000 mtr. at 187.5 kBit/s).
If you use the converter, you need a 1:1 extension cable at the RS485 site because the converter uses the power supply from the MPI interface.
there is no problem doing so. i have a scada & S7-300 connected whit 50m cable, i used a profibus standard cable (green + red wires), the wires should be connected in the D type in pins 3&8. if the lenght is longer you should check the baudrate (decrease it in longer cable)
If you have connected S7300 plc in MPI port your network protocol is MPI, not PPI, otherwise if the connection to pc is alllowed to DP port (if there's one - only 313C-DP, 314C-DP, 315-DP, 316-DP and 318 DP have one on cpu, in every condition if you have only one db9 connector this is MPI, if there's one on right of this this is DP connector).
Siemens suggest that maximum lenght on MPI network is 1000 metres on AWG24 shielded TP (1 x 2 x 24AWG) cable with no more than 60pF/mt capacitance and impedance measured on 100-120 ohm.
Where I work we have tested on shield cable that MPI runs well at least with 60 metres of this cable(is possible that the lenght can be increased): we have used no-profibus cable for no avaiability at moment of installation of plant, but the cable is be substitute due to our standard.
I hope this helps you, but you can contact me directly.
Best regards
