Hello everybody!!!

I am automation engineer and this is the first time I am involving with PLC (Siemens S7, S5) communication interfaces!

First of all I would like to know the differences (a brief technical description) between PPI and MPI protocol. The only thing I know is what abbreviations means (MPI = Multi Point Interface and PPI = Peer to Peer Interface), I think so!

I have 2 PLCs S7-221 with RS485 interface and I want to establish an RF communication between these! Also I have 2 modems SATEL 3AS model. Where should I connect the modems? On PG port or on RS485 Port?

Is there any technical manual about this points?

Any help will be appreciated!!!
Thanks a lot in advance!!!!!!

 

I think PPI = Point to Point Interface.

PPI is for S7-200 network, and MPI is for S7-300&400. You can also communicate between s7-300 and S7-200 using MPI.

The instructions netw and netr are for S7-200 PLCs to communicate to each other. For the modem communication, I once communicated PG and S7-200 using Modem. In fact, you can download the system manual for S7-200 from Siemens website, that will be helpful.

Brian

 

In a Siemens catalog there was a diagram showing a PPI setup and another for an MPI, what I couldn't get is that they both had several items on the network. Both diagrams were similar, so I'm too wondering: where does PPI differ from MPI (with regard to "multi-ness"!!!)?

 

Yes, PPI allows multi-masters etc.

But the PPI timing is not as tight as MPI, so in PPI one CPU can do comms and control, meaning lower-cost & slower comms. In MPI special co-processors must offload comms from main CPU, so cost is higher, but comms can be much faster.

- LynnL

 

The Parallel Peripheral Interface (PPI) is a peripheral found on the Blackfin embedded processor. The PPI is a half-duplex, bi-directional port that is designed to connect directly to LCDs, CMOS sensors, CCDs, video encoders (video DACs), video decoders (video ADCs) or any generic high speed, parallel device.

The width of the PPI is programmable and can be set between 8 and 16-bits in 1 bit increments. The latest Blackfin family (BF54x) also features an 18/24-bit PPI for direct connection to RGB LCD panels.

The PPI can run from 0 MHz up to 66 MHz.

The PPI has a dedicated clock pin, three multiplexed frame sync pins, and between 16 and 24 data pins.