KEYENCE N-400 - Manual (Page 69)

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Chapter 4 Multi-Drop Link Mode Control Procedure
4
4.2 Data Communication in Multi-Drop Link Mode
In multi-drop link mode, the bar code data read by the BL series is sent to the host
computer through either “Auto polling” or “Manual polling”.
The following sections describe these polling methods individually.
You should normally use auto polling mode.
4.2.1 Auto polling
■ Auto polling mode
When the ID numbers of the BL series connected to the N-400 have been regis-
tered in auto polling mode, the N-400 automatically executes polling (queries the
BL series of the specified ID number about its data). The obtained data is con-
stantly sent to the host computer from the N-400.
Since the N-400 automatically queries the BL series about its data, the host com-
puter can be operated using a simple program.
■ Communication format
In auto polling mode, the N-400 sends the read data to the host computer in the
following format:
• mm = 01 to 31: ID number of BL series
• (Data) = Read data
OVER: “BUFFER OVERFLOW” error has occurred. (
➮ See p. 63.)
• Select the header and delimiter from the following formats. The header and
delimiter can be changed to any string of five characters or less.
Header: [ESC], [STX], None
Delimiter: [CR], [CR][LF], [ETX]
■ Setting auto polling mode
To set auto polling mode, use the N-400 setup software ( ➮ see p. 42) or serial
commands ( ➮ see p. 71).
Using the serial commands, you can easily control auto polling (stop or start auto
polling).
N-400
Header % P 03 – ABC123 Terminator
• • •
The BL series with ID
No. 3 reads bar code
data as “ABC123”.
Header % P mm – (Data) Terminator