The older Modbus systems limited the number of objects of each type to 9999.
I.e. Max Input Register = 39999 and Max Holding = 49999
Whereas the protocol has space to read up to 65535 objects of each type. Older Modbus systems imposed a stupid validation and choked the address space to the 9999 limit. Newer systems like the CAS Scanner do not choke the address space and you can read any registers.
To read address Holding Register = 512345 (also known as Holding Reg with offset 12345 in PDU terminology)
Display of the request – we show both the 5 and 6 digit address.