CHAPTER 13 RS-485 COMMUNICATIONS

(3) Message examples

Monitor data: shows a message example to read out a feedback position.

<Query example>

Station No.

FC

Information

Address

No. of registers

CRC check

1 byte

1 byte

2 bytes

2 bytes

16 bits

(2 bytes)

01 ･･･

03

10 ･･･

06

00 ･･･

02

20

CA

When the amplifier station no. is "1".

Specify 1006h as the address of a

feedback position.

Specify 0002h as the number of data 1×2.

<Response message example>

Station No.

FC

No. of data bytes

1 byte

1 byte

1 byte

Information

Data 1

4 bytes

CRC check

16 bits

(2 bytes)

01

03

04 ･･･

00 ･･･

01

86

A0

C9

EB

1×4 = 04h

000186A0h = 100000 units

Data 1 will be FFFE7960h with -100000

units.

 FC 10h (Write of various data)

(1) Query from the master

Station No.

FC

1 byte

1 byte

Address

2 bytes

･･･

(H) ･･･

(L)

10h

Specify the data address.

* For the addresses, refer to the table

13-1.

No. of

registers

Information

No. of

data bytes

Data 1

~

Data n

CRC check

2 bytes

(H) ･･･

(L)

･･･

1 byte

4 bytes

~

4 bytes

16 bits

(2 bytes)

(HH) ･･･

(HL)

(LH)

(LL)

(HH)

(HL)

(LH)

(LL)

(L)

(H)

Specify the number of sets of data n × 2.

* Specify n × 10 on the positioning data.

* The max number of parameters and

positioning data is 9, and 45 for

others.

n × 4

* The positioning data are n × 20.

Write data for n sets from the specified

address

* The positioning data are 20 bytes per

data.

* For the data format, refer to the table

13-1.

Modbus RTU Communications 13-7

13