Xylem H-3521 - Manual (Page 56)

B-4 Modbus Protocol
H-3531
B.4.8 Set Current Stage(WO)
This holding register allows the user to set the current stage by writing the current stage
value to this register. Reading this register is not applicable. This holding register is a 64-
bit holding register, therefore the value sent to write to this register must be in a 64-bit
floating point number format. As shown in the table there is also a 32-bit floating point
number register for this command.
Example Reading Holding Register Command:
Format: “aabbccccddddeeee”
Where: aa = 1 byte Modbus address
bb = 1 byte function code
cccc = 2 byte start address
dddd = 2 byte quantity of registers
eeee = 2 byte crc check
example: 010300010001xxxx
Example Writing Single Holding Register Command:
Format: “aabbccccddddeeee”
Where: aa = 1 byte Modbus address
bb = 1 byte function code
cccc = 2 byte start address
dddd = 2 byte or dddddddd 4 byte register data value
eeee = 2 byte crc check
example: 010600010001xxxx
Example Reading Input Register Command:
Format: “aabbccccddddeeee”
Where: aa = 1 byte Modbus address
bb = 1 byte function code
cccc = 2 byte start address
dddd = 2 byte quantity of registers
eeee = 2 byte crc check
example: 010400010001xxxx
B.5 Input Registers