G_H

So a question I have now is do both Masters receive the data at the same time? in other words are there any timeing issues using this method?

Thedata willbe received by both DP Masters at the same time, as far as the Profibus is concerned.

As an example,let's assume the following:
DP Master 1 "owns" the DP Slave and as such isnot only resposible for its configuration on startup, but also for its cyclic polling.
DP Master 2 is configuredto also readsome or all of the DP Slaves inputs.

What then happens is this:
DP Master 1sends out atelegram to the DP Slave which contains the status of theDP Slavesoutputs.
The DP Slave receives it and issues a response message that contains the status of itsinputs.
This response telegram now "travels" on the Profibus and is"seen" by all stations (due to the serial half duplex nature of Profibus).
DP Master 1 is obviously waiting for this response message and will use it (and then move on to poll itsnext DP Slave).
DP Master 2 simply "listens in", realises that this is a response message from DP Slave xyz andusesthe part of the message that he's interested in too (i.e. some or all ofit's input status).

In sums: For all intents and purposes, both DP Masters get the DP Slaves input status at the same time (only subject to physical location of the DP Masters on the bus and signal travel time on the cable which we can deem to be negligible).
The "biggest" delay/difference you will get is the update of the inputs in each DP Master aseach CPU maintains their own OB 1 cycle.

I hope this helps