Command And Response Frame Structures; Command Frame Structure; Response Frame Structure - Omron V720S Series Operation Manual

Command and Response Frame Structures

5-2

Command and Response Frame Structures

5-2-1 Command Frame Structure

The Reader/Writer continuously receives signals from STX through ETX, and executes the com-
mand when the correct node number is received (*1). If, after receiving an STX signal, another STX
signal is received before an ETX signal is received, the second STX signal is given command prior-
ity.
Node No.
STX "
1
Name
STX
Node No.
Command Code
Option
ETX
BCC

5-2-2 Response Frame Structure

Node No.
STX "
1
Name
Node No.
Retry Flag
Command code
Response Code
Text data
Command Code
" " "
2 2
Description
Indicates the beginning of a communication frame (text). Expressed by
ASCII code 02h.
Indicates the Reader/Writer to communicate with by its node No. This
number can be set within the range between 00 and 31 decimal.(*1)
Indicates the command that the Reader/Writer executes. For the com-
mand codes that are available, refer to Command Code List in 5-2-3.
Makes specified optional settings or specifies read/write data. For details,
refer to the format of the appropriate command.
Indicates the end of a communication frame (text) Expressed by ASCII
code 03h.
Stands for Block Check Character (hereinafter referred to as "BCC"). The
result of the horizontal parity calculation from immediately after STX
through ETX is expressed using one character. You can enable or dis-
able the BCC command using the communications port setting com-
mand.For BCC calculation method, refer to 5-2-5 Example BCC Calcula-
tion.
Note COM2 is a port for setup and can communicate without depending on a node No.
Retry Flag Command Code Response code
" " " "
2 1 2
Description
Indicates the node No. that has been assigned to the Reader/Writer.
This flag will be set to "0" when ACK/NACK control has been disabled.
In ACK/NACK control, a response will be re-transmitted with the retry flag
set to "1" if, after returning a response, ACK has not been received within
a pre-determined period of time or if NACK has been received.
Indicates the code of the command that the Reader/Writer executed.
Indicates the result of command execution.
Refer to 5-2-4 Response Code List for different response codes.
Sent in response to specific commands. For the content, refer to the
frame structure of each command.
Note The contents of STX, ETX, and BCC are the same as those in command
frames.
Option
" " "
2
BCC
ETX
1 1
Text data
ETX
1
Section 5-2
BCC
1
5-5