C
C-12 Micro PLC Programmer’s Guide – April 1994 GFK-0804B
Message (04): Read Analog Inputs
Format:
Address Func Error Check
04
Query
Address Func Error Check
04
Normal Response
Analog Input No. Analog Inputs
Starting Number of
Data
Hi Lo Hi Lo
Byte
Count Analog
First
Hi Lo Hi Lo
Input
Query:
An address of 0 is not allowed as this request cannot be a broadcast request.
The function code is equal to 4.
The starting analog input number is two bytes in length. The starting analog input
number may be any value less than the highest analog input number available in
the Micro PLC. It is equal to one less than the number of the first analog input
returned in the normal response to this request.
The number of analog inputs value is two bytes in length. It must contain a value
from 1 to 125 inclusive. The sum of the starting analog input value and the number
of analog inputs value must be less than or equal to the highest analog input
number available in the Micro PLC. The high order byte of the starting analog
input number and number of analog input fields is sent as the first byte in each of
these fields. The low order byte is the second byte in each of these fields.
Response:
The byte count is a binary number from 2 to 250 inclusive. It is the number of bytes
in the normal response following the byte count and preceeding the error check.
Note that the byte count is equal to two times the number of analog inputs returned
in the response. A maximum of 250 bytes (125) analog inputs is set so that the entire
response can fit into one 256 byte data block.
The analog inputs are returned in the data field in order of number with the lowest
number analog input in the first two bytes and the highest number analog input in
the last two bytes of the data field. The number of the first analog input in the data
field is equal to the starting analog input number plus one. The high order byte is
sent before the low order byte of each analog input.