CAI 700 NDIR, Руководство оператора

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700 NDIR Analyzer 6-20-2017
176
Modbus Command Function Codes
Code 01
This function code is used to read from 1 to 2000 contiguous status bits in a remote device.
The requesting remote device specifies the starting address, including the address of the first bit
specified and the number of bits. The device bits are addressed starting at zero. Therefore, bits
numbered 1-16 are addressed as 0-15.
The bits in the response message are packed as one bit per bit of the data field. Status is indicated
as 1 = ON and 0 = OFF. The LSB of the first data byte contains the output addressed in the
query. The other bits follow toward the high order end of this byte, and from low order to high
order in subsequent bytes.
If the returned output quantity is not a multiple of eight, the remaining bits in the final data byte
will be padded with zeros (toward the high order end of the byte). The Byte Count field specifies
the quantity of complete bytes of data.
Request
Function Code 1 Byte 0x01
Starting Address 2 Bytes 0x0000 to 0xFFFF
Quantity of Bits 2 Bytes
1 to 2000 (0x7D0)
Response
Function Code 1 Byte 0x01
Byte Count 1 Byte
N*
Bit Status n Byte n = N or N+1
*
N = Quantity of Outputs / 8, if the remainder is different of 0
⇒
N = N+1.