KEYENCE N-400 - Manual (Page 70)

Chapter 4 Multi-Drop Link Mode Control Procedure
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4.2.2 Manual polling
■ Manual polling
When you send a polling command from the host computer to a desired BL series
while in manual polling mode, the BL series sends back its data to the host compu-
ter.
In manual polling mode, the host computer is operated with a more complex
program than in auto polling mode, because the host computer executes the
polling. However, manual polling mode allows data to be sent back to the host
computer only when the host computer can receive the data. For this purpose,
manual polling mode is useful. (In auto polling mode, data is constantly sent to the
host computer regardless of the conditions of the host computer.)
When auto polling is not performed (when the BL series’ ID numbers have not
been registered with the N-400 setup software), manual polling mode can be used.
■ Sequence and format for communication
In manual polling mode, data is sent in the following sequence and format:
1. Send a polling command from the host computer.
2. The BL series sends back its bar code data.
• mm = 01 to 31: ID number of BL series
• (Data) = Read data
e: This code is sent back when the BL series has read no data.
OVER: “BUFFER OVERFLOW” error has occurred. ( ➮ See p. 63)
NC: The BL series with the specified ID number does not exist, or is not con-
nected for communication.
SERR: Communication error has occurred.
N-400
Header % P 05 Terminator
Header % P 05 – 123456 Terminator
• • •
The BL series with ID
No. 5 reads bar code
data as “123456”.
Header % P mm Terminator
Header % P mm – (Data) Terminator