Instruction Manual

5. Modbus RTU
98
Modbus
(4) Query sample
A sample query that reads the current speed monitor (from address 900A
H
) of a controller of axis
No. 0 is shown below.
z Query (silent intervals are inserted before and after the query)
01 03 90 0A 00 02 C9 09
Field RTU mode
8-bit data
Start Silent interval
Slave address [H] 01
Function code [H] 03
Start address [H] 900A
Number of registers [H] 0002
Error check [H] C909 (in accordance with
CRC calculation)
End Silent interval
The response to the query is as follows.
z Response (silent intervals are inserted before and after the response)
01 03 04 00 00 03 E4 FA 88
Field RTU mode
8-bit data
Start Silent interval
Slave address [H] 01
Function code [H] 03
Number of data bytes [H] 04 (4 bytes = 2 registers)
Data 1 [H] 00 00 03 E4
Error check [H]
FA88 (in accordance with CRC calculation)
End Silent interval
The current speed is “000003E4” o Convert into decimal number o 996 (x 0.01 mm/sec)
The current speed monitor is 9.96 mm/sec.
Example 2) : When the current speed reading is “FFFFFF35” (moving in the direction opposite
to the example above) o
FFFFFFFF
H
– FFFFFF35
H
+ 1 (make sure to add 1) o
Convert into decimal number o 203 (x 0.01 mm/sec) o
The current speed is 2.03 mm/sec.
Note The data of the response example is simply an example and will vary depending on
various conditions.