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Communication protocols
Modbus > Modbus Master - Function codes
6.4.4.2
FC 02 - Read Input Status
60
The driver enters the data of the reply message into the destination DB word-by-word.
The 1. received byte is entered as the low byte of the 1. word "data[1]", the 3. received
byte as the low byte of the 2. word "data[2]", etc.
If a quantity of less than 9bit or if only one low byte was read, the value 00h is entered
into the remaining high byte of the last word.
This function serves to read individual bits of the input area of the slave.
DB SEND source
Address
Name
+0.0
ADDR
+1.0
FUNC
+2.0
start_addr
+4.0
bit_number
n
start_addr
–
start_addr is not checked by the driver and is sent unchanged.
n
bit_number
–
Any value between 1...2040 (ASCII: 1...2008) is permitted as bit_number.
DB RCV destination
Address
Name
+0.0
data[1]
+2.0
data[2]
...
...
n
The driver enters the data of the reply message into the destination DB word-by-word.
n
The 1. received byte is entered as the low byte of the 1. word "data[1]", the 3.
received byte as the low byte of the 2. word "data[2]", etc.
n
If a quantity of less than 9 bits or if only one low byte was read, the value 00h is
entered into the remaining high byte of the last word.
VIPA System 300S
Type
Comment
BYTE
Slave address
BYTE
Function code
WORD
Bit start address
INT
Amount of bits
Type
Comment
WORD
Data
WORD
Data
...
...
HB130 | CP | 341-1CH01 | en | 18-40
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