Some systems (e.g. Trend Synapsis SIP, Xenta 913) may require the use of the Modbus address notation (Modicon Modbus convention), with 3xxxx and 4xxxx notation for Modbus Register References and a 1 offset between the Register Reference and the actual modbus register address. Our products use the actual register address to avoid confusion. We also do not use the 3xxxx and 4xxxxx Register References and simply refer to Holding Registers and Input Registers.
If your system is set up with this notation and incorrect values are read then test with adding an offset. e.g. for H0001 use 40002.