Chapter 13. Dedicated Cnet communication for GM6
13 - 15
Table 13.7 Available direct variables
Available direct variable
Number of data
Byte(B)
%MB,%QB,%IB
1
WORD(W)
%MW,%QW,%IW,%(P,M,L,K,F,T,C,D,S)W
2
DOUBLE WORD(D)
%MD,%QD,%ID
4
•
In data area, the value converted from hex data to ASCII code is entered.
(4) Response format(for PLC NAK response)
Format
name
Header
Station No.
Command
Command type
Error code
(Hex 2 Bytes)
Tail
Frame
check
Frame
(Ex.)
NAK
H10
R(r)
SB
H1132
ETX
BCC
ASCII
value
H15
H3130
H52(72)
H5342
H31313332
H03
•
Station number, commands, and type of command are the same as computer request format.
•
BCC : When main command is lower case(like ‘r’), only one lower byte of the value resulted by adding ASCII
values from NAK to ETX is converted into ASCII, added to BCC, and sent.
When main command is upper case(like ‘r’), BCC is not used.
•
Error code is hex and 2 Bytes(ASCII code, 4 Bytes), which indicates type of error. For the details, see Appendix
'B. Error Code Table'.
Ex.1
When memory type included in direct variable name of computer request format is W(WORD), and data number of
computer request format is 03, data number of PLC ACK response after execution of command is indicated by
Ex.2
In just above example, when data contents of 3 WORDs are 1234, 5678, and 9ABC in order, actual ASCII code
converted values are 31323334 35363738 39414243, and the contents is to be entered in data area.
