Thanks for your detailed response. Interesting note on modbus, I am personally still quite new to the protocol so it is definitely useful to learn the small intricacies of the protocol.
I did exactly what you pointed out: I enabled the different settings on the com port and could see that both Rx and Tx was being registered for D17, but for D30 (new device), only Tx was being registered. So, apparently DAQFactory was not receiving a response from the device. I changed the offset for D30 to 0.5 and it seems to be working better now, although I still get timeouts every ~5mins or so. I think this means that the offset / delay is accumulating and then it causes a timeout, if you understand what I mean. Ideally, this works without the timeouts, but if there are no other solutions that you can think of then it is manageable. Thanks in advance for any additional input you can provide.
(I didn't adjust the offset for D17 since I didn't think it is the one causing the problem and I didn't adjust the SetDelay() method either for these tests)