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C-10 Micro PLC Programmer’s Guide – April 1994
GFK-0804B
Message (02): Read Input Table
Format:
Address Func Error Check
02
Query
Address Func Error Check
02
Normal Response
Point No. Points
Starting Number of
Data
Hi Lo Hi Lo
Byte
Count
Query:
An address of 0 is not allowed as this cannot be a broadcast request.
The function code is 02.
The starting point number is two bytes in length. It may be any value less than the
highest input point number available in the Micro PLC. The starting point number
is equal to one less than the number of the first input point returned in the normal
response to this request.
The number of points value is two bytes in length. It specifies the number of input
points returned in the normal response. The sum of the starting point value and the
number of points value must be less than or equal to the highest input point number
available in the Micro PLC. The high order byte of the starting point number and
number of bytes fields is sent as the first byte. The low order byte is the second byte
in each of these fields.
Response:
The byte count is a binary number from 1 to 256 (0 = 256). It is the number of bytes
in the normal response following the byte count and preceding the error check.
The data field of the normal response is packed input status data. Each byte
contains 8 input point values. The least significant bit (LSB) of the first byte contains
the value of the input point whose number is equal to the starting point number
plus one. The values of the input points are ordered by number starting with the
LSB of the first byte of the data field and ending with the most significant bit (MSB)
of the last byte of the data field. If the number of points is not a multiple of 8, then
the last data byte contains zeros in one to seven of its highest order bits.