1756DHRIO connet 1771-ASB

Use Controllogix to upgrade Softlogix system, 1756DHRIO connet 4 1771-ASB module, how to read and write the IO with Remote IO module?

That depends on what kind of I/O it is, in general, to read a digital input, use something like:

DHRIO_CH_NAME:TYPE_I_OR_O.Data[SLOT_NUM].BIT_NUM

Where DHRIO_CH_NAME = the configured name for the rack in the IO list, TYPE_I_OR_O = I for input, O for output, SLOT_NUM = the rack logical slot number, and BIT_NUM = the bit number.

Ex: RIO5BP:I.Data[3].12
RIO5BP:O.Data[2].01