Time machine cannot back up to drobo, says read only

How do I get my 5 D drobo to backup, the message I get is 'read only"

Here’s what the Drobo KB has to say on that issue.

Drobo is suddenly read-only

Thank you I have tried the first two suggestions with no joy

What I’d try at this point then is, pull any ordinary data you have off temporarily, do a factory reset from dashboard, set it up again making sure to enable the backup volume & point time Machine at that rather than the main storage. Then put any data you pulled off the main storage back on.

Manuals for how to do all those things are here:
Drobo Online User Guide

Thank you very much, I will get my repair guy to tackle this