RS485 Experts

I have installed several RS485 networks with several nodes on each
network. Always with the master at one end and daisy chained out to
each node. Termination resistors at each end. Question: can the
master be in the middle or somewhere other then one end ?

Yes!

Thanks,
Thats the kind of answer I like.

Aw, guest, You're ruining our racket with those simple, concise answers!

You can play a lot of games with RS-485 that aren't strictly according to Hoyle but work anyway. I've had networks with three branches off the master, and a couple of sub-branches off the branches. They work fine, although you have to be willing to play around a bit with terminating resistors and such. Obviously you can get away with more on a short network than on a long one.

Yes, there are some rules regarding RS485 network.

Like:
- Max 32 nodes on each segment
- Each segment must be a line structure. Branched-, tree- or star-structure isn't allowed since each segment can only have two end stations. (But repeaters can be used to make those structures)
- max length of a segment with respect to transmission speed, line section and quality
- max lenght of stub cables on each node/segment
- etc

Which one of those rules above are broken if you place the master in the middle or other places then the end??

Regarding the line structure? Because you then have a "2-branched" structure????

Isn't the structure still a line? With only two ends. The answer is YES.

Of course there should have been an additional remark that since the master isn't a end station any longer, there shall not be a termination resistor on the master station. But that I am sure you was aware of!