Omron Programmable Terminals NT631C - Manual (Page 55)

38
Connecting a Bar Code Reader Section 3-4
About RS/CS Control
During bar code reading, the NT631/NT631C performs RS/CS control. When
the Input Method setting of the NT631/NT631C is set to Auto, the RS signal is
turned OFF, prohibiting the next input, until the read data has been sent to the
host as notification.
Because of this, when the Auto setting is made, the next input is not possible
until the data has been sent to the host as notification.
However, when the setting is Auto and the RS/CS signals of the cable are
shorted, RS/CS control is ineffective. Consequently, data input from the bar
code reader to the NT631/NT631C is updated regardless of whether or not
the data is sent to the host as notification.
For details, refer to the instruction manual for the bar code reader used.
3-4-3 Data Format
The data format for communications when using the bar code input function of
the NT631/NT631C is shown below.
The characters which are effective as data are hexadecimal codes from 20 to
7FH, and the maximum data length is 40 bytes.
Data which does not follow the data format described above is invalidated and
discarded.
Preamble STX
Postamble ETX
RS/CS control Available
Communications protocol No-protocol mode
Transmission of number of bar code label digits Transmission prohibited
Transmission of ID characters Transmission prohibited
Bar code types Multi-reading (all types can be
read)
Trigger switch setting Automatic reading mode
Item Possible Settings
Data Data Data STX ETX
(03 H ) (02 H )