KEYENCE N-410 - Manual (Page 83)

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4-2 Multi-drop Link Mode Data Communication
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Send Buffer Capacity
(N-410 send buffer)
The N-410 send buffer can hold up to 3000 items (up to 100 KB). If the buffer capacity is
exceeded, a buffer overflow error such as the one below will be sent to the host computer and all
send buffers will be cleared. (Error number "96" will display on the N-410)
When using SR Series or RF Series devices, the buffer will not be large enough to hold
3000 transmissions if the data size (including added data and attribute data) exceed 100
KB.
Send buffers for BL Series, SR Series, and RF Series devices
The BL-1300 Series device has a 8192 byte buffer. BL-700/600/500/180 Series devices have a
400 byte buffer. The BL-210 Series has a one item buffer. The RF Series has a 10 KB buffer.
These buffers hold data while waiting for a query (polling) from the N-410. (The N-410 polls BL/
SR/RF Series devices for the data stored in their buffers.)
If the buffer capacity is exceeded, an error such as the one below will be sent from the BL/SR/RF
Series device to the host computer and all send buffers will be cleared.
BL/SR/RF Series devices that do not have buffer overflows will operate normally.
*mm = 01 to 31: The BL/SR/RF Series device ID number
A buffer overflow indicates that the polling speed cannot keep up with the BL/SR/RF Series
device between data transmissions. This must be handled in a manner such as the following.
• Set the baud rate between the BL/SR/RF Series devices and the N-410 to maximum to reduce
the polling interval.
• Reduce the number of BL/SR/RF Series devices connected to reduce the polling interval.
• Lengthen the BL/SR/RF Series read interval to reduce the amount of data handled by the N-410.
• When using manual polling, BL/SR/RF Series devices should be altered to send a polling command
before a buffer overflow occurs.
• Delete all unconnected ID numbers in the "ID settings" of the N-410.
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