CHAPTER 13 RS-485 COMMUNICATIONS

 FC 17h (Read out/write in various data)

Only addresses 6000H to 600FH are applicable.

An exception response (exception code: 02H) is returned if an address outside this range is

specified.

(1) Query from the master

Station No.

FC

Read out start

address

1 byte

1 byte

2 bytes

No. of registers 2 bytes

Write in start

address

2 byte

No. of registers

Information

No. of data bytes

2 byte

1 byte

Data 1

4 bytes

~

~

Data n

4 bytes

CRC check

16 bits

(2 bytes)

(H)

(L)

(H)

(L)

(H)

(L)

(H)

(L)

(HH)

(HL)

(LH)

(LL)

･･･ 17h

･･･ Specifies the data address.

* Addresses from 6000H to 600FH can be

set.

･･･ Specify the number of sets of data n x 2.

* Up to setting range 1 to 16 for number of

sets of data n

･･･ Specify the data address.

* Addresses from 6000H to 6007H can be set.

･･･ Specify the number of sets of data n x 2.

* Up to setting range 1 to 8 for number of

sets of data n

･･･ n x 4

･･･ Write in data for n sets from the specified

address

* For the data format, refer to the format field

(symbol) in table 4-1.

(HH)

(HL)

(LH)

(LL)

(L)

(H)

(2) Response message from slave

Station No.

1 byte

FC

1 byte

No. of data bytes 1 byte

Information

Data 1

~

4 bytes

~

Data n

4 bytes

CRC check

16 bits

(2 bytes)

(HH)

(HL)

(LH)

(LL)

･･･ 17h

･･･ n x 4

･･･ Read out data for n sets from the specified

Address

** Data read out range: 1 to 16

(HH)

(HL)

(LH)

(LL)

(L)

(H)

13

Modbus RTU Communications 13-13