Hi experts,

In Profibus network, you can adjust some parameter if you select user defined profile (by default the profile is DP).

As I understand, this is primarily to compensate for error detection, especially with some special DP nodes.

But I'm curious, can changes in these parameters affect the data acquisition time? Specifically, can it affect a PID response?

Thank you very much.

Hello G_R_E_Y_31,

the PROFIBUS parameter settings have an effect in several ways. 

As PROFIBUS is a Multi-Master (token ring) bus with underlying Master Slave access method, the settings have an effect on both the communication between masters and masters and their slaves. 
In your screenshot you can see these effects, when you look at the “Ttr-typically” parameter. This is the time a Master has to wait, before that particular Master is able to communicate again with all its slaves. A Master is allowed to hold the token (bus usage rights) for only a certain amount of time (token hold time = Tht). After the time expired, the master has to pass on the token to the next master on the bus, which in turn then can communicate with its slaves (or other masters).

This means, the more masters are on the same bus, the longer the time between token holdings can be, shown in the "Ttr" parameter. This means for the waiting master, it doesn't get any data from its slaves. This again has an effect on a possibly running PID controller in the masters software, as it starves during the time the master doesn't hold the token.

Recommendation is to setup the PID controller with a sample rate, which is not faster then the “Ttr-typically”. Reduce the number of masters on the same bus to a minimum. Keep the number of slaves (and their exchanged data) as low as possible. These measurements will make your PROFIBUS system respond faster.
Btw, Panels and PG's are also masters on the bus. Whenever possible separate the programming and monitoring (HMI) networks from the production (I/O) network.