User Manual

60 MODBUS Programmable I/O NA-9379 FnIO S-Series
Copyright(C) CREVIS Co.,Ltd Support [phone] 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.