KEYENCE BL-180 - Manual (Page 99)

Power Supply BL-U1
93
5 Communication
5.1 Outline of Communication types
You can perform all multidrop link communication by sending commands from the
host computer to the BL series.
The communication of the multidrop link is classified into the following two types:
Data communication
For sending read data from the BL-series to the host computer. When data re-
ceive commands (polling commands) are sequentially sent to each BL series con-
nected to the host computer, the read data is sent to the host computer.
The read data is stored in the BL series’ transmission buffer, and the data stored
in the transmission buffer is called using the polling command.
Command communication
Using serial communication commands allows direct control of the BL series or
change/confirmation of the BL series’ settings.
5.2 Communication Format
All multidrop link communication is done in the following format. Send any com-
mand in this format and the BL Series will respond in the format shown below.
Detail of each data:
1 , 6 Delimiter: All the data should start with [STX](02h) and should end with
[ETX](03h). This cannot be changed.
2 mmm/No. of data: Total number of characters of above data 2 to 5
should be entered. (Do not count [STX] and [ETX].)
When you send [STX][mmm][03][SSET][cc][ETX], for example, the num-
ber of characters will be; 3+2+4+2=11Thus, [mmm] is 011.
3 nn/ID No.: Specify the ID No. of the BL Series reader you want to send/
receive. ID Nos. should be from 01 to 31.
4 Data/Command/Response: Two commands can be used for multidrop
link communication. [P] for polling and [C] for clearing data.
5 cc/Checksum: Add the checksum when you send the data. When the re-
sponse is returned from BL, the checksum follows the data. Determine
the checksum by calculating the Exclusive OR of each data from
2 to 4
as follows.
STX mmm nn Data/Command/Response cc ETX
Delimiter No. of data ID No. Contents of data Checksum Delimiter
1 2 3 4 5 6
Name Command Response Description
Polling com-
mand
P
Data is
returned
if any
data is
stored.
[e] is
returned
if no data
is stored. [OVER] is
returned if
the buffer is
full. Command to ask
whether the BL series’
transmission buffer con-
tains any data.
Data clear
command
C
[OK] is returned if
the data is cleared.
[NG] is
returned if
the data has
been
already
cleared.
This command clears
one piece of the sent
data, and completes a
series of data communi-
cation.