Unipulse F331 - Page 51

42
7 OPTION
42
OPTION
Chapter
7
03 (0x03) Read holding registers
Contents of slave holding registers are read.
No broadcast can be specified.
Specify the holding register start address and number of registers.
The slave transmits the contents of one register as expanded in double bytes.
* N = Number of registers
Example) Read the contents from HI limit (address 40002) to LO limit (address 40003).
Keep in mind that the relative address for reading the HI limit value is 0x01.
The example shows the case where the F331 settings are as follows:
04 (0x04) Read input registers
Contents of slave input registers are read.
No broadcast can be specified.
Specify the input register start address and number of registers.
The slave transmits the contents of one register as expanded in double bytes.
* N = Number of registers
[Request]
Function 1 byte 0x03
Start address 2
bytes 0x0000 - 0xFFFF
Number of registers 2 bytes 1 - 125 (0x7D)
[Response]
Function 1 byte 0x03
Number of data bytes 1 byte 2×N *
Register value N×2
bytes
[Error response]
Error code 1 byte 0x83 (function + 0x80)
Exception code 1 byte 01 or 02 or 03
[Request]
Function 03
[Response]
Function 03
Start address; higher 00 Number of data bytes 04
Start address; lower 01 HI limit; higher 00
Number of registers; higher 00 HI limit; lower 64
Number of registers; lower 02 LO limit; higher 00
LO limit; lower 32
HI limit
100 (0x0064)
LO limit 50 (0x0032)
[Request]
Function 1 byte 0x04
Start address 2 bytes 0x0000 - 0xFFFF
Number of registers 2
bytes 1 - 125 (0x7D)
[Response]
Function 1 byte 0x04
Number of data bytes 1 byte 2×N *
Register value N×2
bytes
[Error response]
Error code 1 byte 0x84 (function + 0x80)
Exception code 1 byte 01 or 02 or 03