KEYENCE N-410 User Manual
Page 123
7-7
7-2
Device Assignments
PLC
7
Real time control
• Write either 0000 or 0001 to this area.
• This will be 0001 when the code reader is reading the barcode or the N-410 is writing to the PLC.
• This returns to 0000 after data has been written so that new data can be written in the A+01 to +130
addresses.
In other words, if the A+00 address contains 0000, the data is valid.
(Example 1)
The A+00 address is normally 0000.
This becomes 0001 while data is being written, so when it become 0000 (at startup), the A+01
to +130 addresses should be handled by program.
(Example 2)
The A+00 address is normally 0001.
The A+00 address becomes 0000 when data ends, so the A+01 to +130 addresses should be
handled by program.
After this is handled, be sure to reset the A+00 address to 0001. This allows the A+00 address to act as
a trigger for new writing new data when it is set to 0000.
If barcodes or 2D codes are read consecutively, "real time processing" may allow data in
the PLC to be overwritten before it is processed. If this is the case, use of "sequence
processing is recommended".
Sequence processing
• Write either 0002 or 0003 to this area.
• If the A+00 address is 0002, new data can be written.
• This changes to 0003 after data has been written so that new data can be written in the A+01 to +130
addresses.
• After program processing, set this back to 0002. If this is not set back to 0002, new data will not be
written.
• Data that cannot be written is stored in the send buffers of the connected code readers. When using
sequence processing, the send buffer on the N-410 is not used and the data is saved in the send buffer of
the code reader. If the capacity of the buffer is exceeded, a buffer overflow will occur and "OVER" will be
written.
If the code reader at one ID number is holding (i.e., the flag area is 0003), data can still be
written to other code readers (if the flag areas on those devices are 0002).
In other words, each ID number acts independently during sequence processing.
Note
Reference