ProfiBus DP


Thread Starter

Ivan Lam

We are currently using a Simatic TI 555 PLC with integral ProfiBus DP port. All the I/O we are using are those ET200M ProfiBus I/O connecting to that DP port. We now want to have some HMI panel connect to the system all around the workshop. Can anybody tell whether it is ok to mix those HMI with those I/O using the same DP port/cable? If it is ok, any software necessary? (The Siemens catalog are so confusing that we cannot arrive at a conclusion.)

Daniel Chartier

From my experience with Profibus and TI545/555 PLCs, I can tellyou that it is easy and ok to mix IO and HMI on the DP network. We have done so using Siemens OPs, Quickpanels from TCP, Uticor and Maple systems, so I know it can be done.

However depending on the manufacturer's planning, these HMIs can be inserted on the Profibus-DP network either as slaves (you then have to declare them as such in a configuration program, such as ComProfibus, where you give them a Profibus address, a number of input and output words, and import (merge) to the TI configuration or as Class2 Masters (this happens with the siemens OP/TPs). In that case they must be configured on their own software (Protool, in the case of Siemens HMI).

Note that you must always limit the number of HMI on Profibus if they are class2 Masters, because you can then not predict the impact they will have on communications (you don't know beforehand the number of I/O words they will request, which throws the Profibus schedule out of whack).

Hope this helps,
Daniel Chartier