We assumed the relays were mislabeled and it is no problem. If you could reply here when the documentation is updated that would be helpful.
Thanks Tomas

@Alessandro
lbcm2835 is used to access I/O pins on the Pi. UniPis do not use GPIO to handle output. There are internal ARM processors which are connected to the Pi via an SPI bus that handle the system's IO. The easiest way to access the relays would be to install the neuron tcp modbus overlay as stated above and access the relays through a c++ modbus library.

The documentation in the downloads section does not provide information about all the labeled I/O located on the device. Specifically the difference between AI and AIS as well as AO and AOV. Is there more up to date documentation available? Or could you provide us with these specs?

Thanks

On a side note, we recieved 2 M503s. On each, RO2.2 and 2.3 are labeled twice, should they actually be 2.4 and 2.5 instead?