Profibus cycle time

Hello Gedas

the Slot Time (Tslot) is the maximum time the DP Master waits for a response from a DP Slave. Your wireless device obviously requires a very high value and may in fact need rather loooong before you get a response. Because you have to set it this high, Step 7 will use it to calculate all other values like Ttr and DP Slave watchdog and I agree, these values are a bit insane.

Having said that, while the DP Master is allowed to wait a long time for a response from each DP Slave, all directly DP Slaves will respond as fast as they normally do and your Step7 calculated Ttr is thus misleading.

Last but certainly not least, I suggest you have a look at PROCENTEC's Profiswitch X5. This device allows you to run different Segments of one Network at different speeds and may just be what you were looking for (it certainly would be my choice to solve this, but then again, I am biased and will need to get the disclaimer out of the way, but should you happen to be located in the Australasian region, feel free to get in touch with the good guys from I S Systems who are the local PROCENTEC partner and they'll help you out).

I hope this helps

Good question Juergen and the simple answer is that the DP Master will NOT wait 5700ms for an answer from the DP Slave.

Put simple, the ProfiSwitch X5 acts as a data buffer for the DP Slaves that are located on a Segment that has been set to a different baudrate than the Main channel. Even though the underlying DP Slaves Node addresses are directly "visible" for the DP Master, the DP Master will in essence poll the X5's internal buffer rather than the underlying DP Slave directly. This ingenious feature allows you to have one DP network that has different Segments at different baudrates (and it makes the X5 rather unique). 

It does though also mean that there are certain things to be aware of when using the X5 as it is NOT fully transparent when a Segment is set to operate at a different baudrate. For example, while you can connect another DP Master to a Segment that is set to a different baudrate, that DP Master can only "see" the DP Slaves that are on his Segment (which also means you can NOT connect a HMI to a Segment that is set to a different baudrate and expect it to be able to read data from the PLC on the main Segment)

Other things to be aware of are:

• The retry limit is automatically set to 5 for Segments that operate on a different baudrate (which is good as it "immunizes" these against short lived interference)
• Bus timings are automatically set for these Segments and can not be changed.
• DP Slaves Watchdog times are calculated based on the set/selected DP Master Watchdog time and thus can be adjusted
• You can NOT use address 1 on Segments that are set to operate at a different baudrate
  
• The X5 itself is a "passive" device (just like any other "normal" repeater) and NOT configured in for example Step 7 HWconfig
  
• Best of all, you still use/operate the X5 as a "normal" ProfiHub when you set the Segment(s) to operate at DP Master baudrate (in which case it is a fully transparent standard repeater which can come to to the "rescue" to change Segment baudrates should the need arise)