KEYENCE BL-600 Series - Manual (Page 122)

Chapter 7 Serial Communication
112
7
Example 1
When the number of bar code digits is
10 (with no additional data)
400 ÷ (10 + 5) = 26
The transmission buffer can store 26
pieces of data.
• PASS and RTRY can be received in either communication format
PASS <CR>(RTRY<CR>) or <STX> PASS <ETX>(<STX>RTRY<ETX>).
*
An <ESC> can also be added to the beginning and an <LF> added to the
end of the format.
Note 1: The BL-600 Series can receive all commands while waiting for a “PASS.”
In this case, the BL-600 Series will send back without waiting for a response to the
command (e.g. OK).
Note 2: When the BL-600 Series receives the “SSET” command ( ➮ See page 116.)
while waiting for a “PASS”, it clears all the data stored in the transmission buffer,
and enters the setting mode.
■ ACK/NAK Handshaking
The ACK/NAK handshaking uses <ACK> (06H) and <NAK> (15H) instead of
“PASS” and “RTRY”, which are used in the PASS/RTRY handshaking. Operation is
the same as that for the PASS/RTRY handshaking, except for the transmission
characters.
■ RTS/CTS Handshaking
•
When the PC’s “RTS” (BL-600 series’ CTS) signal turns off, the BL-600 Series
suspends data transmission. When the PC’s “RTS” signal turns on, the BL-600
Series sends the suspended data.
• The BL-600 Series can still read bar codes even if the PC’s “RTS” signal is off.
In this case, the data is stored in the BL-600 series’ transmission buffer.
➮ See page 112 for its capacity.
Note 1: If the amount of stored data exceeds the capacity of the transmission
buffer, the BL-600 sends back [Header]OVER[Delimiter] to the PC, and clears all
data stored in the transmission buffer. The BL-600 stops operation while clearing
data. It recovers when the RTS of the computer turns ON.
Note 2: The RTS/CTS handshaking cannot be used for RS-422A communication.
Note 3: The RTS/CTS protocol can be used together with other handshaking
protocols.
Note 4: When the PC’s RTS signal is off, the BL-600 does not sends back a
response (e.g. OK [CR]) to the PC.
Capacity of transmission buffer
The BL-600’ s transmission buffer can store 400 bytes (400 characters).
The number of characters stored in the transmission buffer for each data packet is
the number of characters in the data (including additional data such as the number
of decoding match count) plus an additional five characters indicating the data’s
attributes.
When multi label reading mode 2 or 3 is used, these five attribute characters are
added to each data packet.
Attributes of
the data
Example 2
When the number of bar code digits is
20 (with no additional data)
400 ÷ (20 + 5) = 16
The transmission buffer can store 16
pieces of data.
Capacity of
the transmis-
sion buffer
➞ ➞
Attributes of
the data Capacity of
the transmis-
sion buffer
➞ ➞