Chapter 8 Dedicated Protocol Communication
8-11
3) Variable
Input variable’s address to read actually. It shall be ASCII value within 16 characters.
Others than figure, capital/small letter, ‘%’ and ’.’ are not allowed for the variable name.
Notes
(1) Device data type of each block shall be surely identical. If the data type of the first block is Word,
and that of the second is Double Word, an error may occur.
(2) If data type is Bit, the data format will be one byte (HEX). In other words, if BIT value is 0, the
data will be h00 and if the value is 1, the data will be h01.
(3) When Bit write function is used, the address must be calculated in Bit unit.
For example, to write a data in the hC (12
th
) bit of M172 word, the Bit address can be calculated
as follow processing.
Wrong Expression: %MX172C
Right Expression: 172(Word number) x 16 + 12(Bit number) = 2764
%MX2764
(3) Response format (For PLC’s ACK Response)
Format
name
Header
Instruction
Data type
Reserved
area
Error
status
Number of
blocks
Code (Ex.)
...
h0059
h0002
h0000
h0000
h0001
1) Number of blocks
It is the number of blocks normally written.
(4) Response format (For NAK Response)
Format
name
Header
Instruction
Data
type
Reserved
area
Error status
Error code
(Hex 1 Byte)
Code (Ex.)
...
h0059
h0002
h0000
hFFFF
(other than 0)
h21
Notes
1) Error code is attached the type of error in 1 byte of Hexadecimal code.
Refer to ‘Error Codes Table’ for more details.
