A.3.1. 1 (0x01) read coils, Fnio s-series – Beijer Electronics NA-9379 User Manual

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MODBUS Programmable I/O NA-9379

FnIO S-Series



Copyright(C) CREVIS Co.,Ltd Support +82-31-899-4599 URL : www.crevis.co.kr

A.3.1. 1 (0x01) Read Coils
This function code is used to read from 1 to 2000 contiguous status of coils in a remote device. The Request PDU
specifies the starting address, i.e. the address of the first coil specified, and the number of coils. In the PDU Coils
are addressed starting at zero. Therefore coils numbered 1-16 are addressed as 0-15. The coils in the response
message are packed as one coil per bit of the data field. Status is indicated as 1= ON and 0= OFF.

Request

Field name

Example

RTU

ASCII

ASCII (bus line)

Start of Frame

-

t1-t2-t3

“,”

0x3A

Slave Address

0x07

0x07

“07”

0x30, 0x37

Function Code

0x01

0x01

“01”

0x30, 0x31

Starting Address Hi

0x10

0x10

“10”

0x31, 0x30

Starting Address Lo

0x00

0x00

“00”

0x30, 0x30

Quantity of Outputs Hi

0x00

0x00

“00”

0x30, 0x30

Quantity of Outputs Lo

0x0A

0x0A

“0A”

0x30, 0x41

Error Check (CRC/LRC)

-

0xB8, 0xAB

“DE”

0x44, 0x45

End of Frame

-

t1-t2-t3

CR, LF

0x0D, 0xA

Response

Field name

Example

RTU

ASCII

ASCII (bus line)

Start of Frame

-

t1-t2-t3

“,”

0x3A

Slave Address

0x07

0x07

“07”

0x30, 0x37

Function Code

0x01

0x01

“01”

0x30, 0x31

Byte Count

0x02

0x02

“02”

0x30, 0x32

Output Status

0x55

0x55

“55”

0x35, 0x35

Output Status

0x02

0x02

“02”

0x30, 0x32

Error Check (CRC/LRC)

-

0x8F, 0x6D

“9F”

0x39, 0x46

End of Frame

-

t1-t2-t3

CR, LF

0x0D, 0xA

* In case of address 0x1015~0x1000 output bit value: 00000010_01010101.













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