KEYENCE BL-600 Series - Manual (Page 149)

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Chapter 8 PLC Link
8
Operating procedure
1. To trigger the BL-600 to start reading, set the +04 address to “1”.
2. When the BL-600 recognizes the +04 address, it returns a “0” to the +04 ad-
dress. The BL-600 then starts reading the data.
3. The BL-600 continues reading for the “one-shot signal trigger time” set at the
+06 address.
4. When the BL-600 has read all the bar codes, it writes the new data in A+05 to
A+69.
5. If a reading error occurs, the BL-600 writes a reading error code in A+05 to
A+69.
The memory data flag areas are used to flag that the bar code data has been
stored.
The following two methods are available depending on the application.
■ Real-time processing
•
A number of “0” or “1” is written to the memory data flag area.
• While the BL-600 is reading and writing the bar code data in the PLC’s memory,
the flag area is set to “1”.
• When new data is stored in addresses A+05 to A+69, address A+00 becomes
“0”. In other words, new data is the data when address A+00 changes from a “1”
to a “0”.
• If the bar code reading interval of the BL-600 Series is shorter than that of the
communication in the PLC link, data that has not been written into the specified
area is stored in the transmission buffer of the BL-600 Series.
➮ See page 6-5.
If the amount of stored data exceeds the capacity of the buffer, the entire
contents of the buffer is cleared and an “OVER” is stored in the memory data
area (A+05 to A+09).
If an overflowed buffer error occurs, the BL-600 Series halts operation. It will
resume operation once the “OVER” has been stored.
Example 1
Normally, the A+00 address is set to “0”.
While the BL-600 is writing data, the flag area is “1”. When the flag area becomes
“0”, the data stored in the A+05 to A+69 addresses can be processed.
Example 2
Normally, the A+00 address is set to “1”.
When data writing is completed, the flag area becomes “0”. The data stored in the
A+05 to A+69 addresses can be processed.
Set the A+00 address to “1” immediately after data processing is completed. This
enables the BL-600 to use the point at which the A+00 address becomes “0” as the
trigger for writing new data.
Note: When the BL-600 continuously reads bar codes, the real time processing
mode may replace stored data with new data before the new data is processed in
the PLC. To prevent this, use the sequential processing mode as shown in the next
page.
A+00 (A is the head address in which the data specified in +00 to +03 is stored.)
Memory data flag areas