GE GFK-0804B manual Message 04 Read Analog Inputs Format

C

Message (04): Read Analog Inputs

Format:

Address Func 04

Starting

Analog Input No.

Number of

Analog Inputs

Error Check

Hi Lo Hi Lo

Query

Address Func

Byte

First

Data

Error Check

04

Count

Analog

Input

Hi Lo Hi Lo

Normal Response

Query:

HAn address of 0 is not allowed as this request cannot be a broadcast request.

HThe function code is equal to 4.

HThe 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.

HThe 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:

HThe 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.

HThe 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.

C-12 Micro PLC Programmer's Guide ± April 1994 GFK-0804B