KEYENCE BL-600 Series - Manual (Page 121)

111
Chapter 7 Serial Communication
7
7.2 Details on Data Communication
This section describes the communication protocols and data format for data
communication.
Communication protocols
The BL-600 supports the following four handshaking protocols (types of data
communication).
■ No Handshaking
The BL-600 Series sends read data to the PC without any handshaking proto-
col.
■ PASS/RTRY Handshaking
1. The BL-600 Series sends read data to the PC.
2. The BL-600 Series waits for a response from the PC (PASS: Transmission
succeeded, RTRY: Request to re-send).
3. If “PASS” is sent from the PC to the BL-600 Series, the data transmission is
complete. The BL-600 is ready for the next data transmission.
* The BL-600 Series does not respond to the “PASS” command.
4. If the BL-600 Series receives “RTRY” from the PC while waiting for “PASS”, the
BL-600 Series resends the same data and again waits for “PASS”.
* Once the BL-600 Series receives a “PASS”, it will send nothing, even if
“RTRY” is received from the PC.
5. The BL-600 can continue to read bar codes while waiting for “PASS.” The data
is stored in the BL-600’s transmission buffer. ➮ See page 112.
Note: If the amount of stored data exceeds the capacity of the transmission buffer,
the BL-600 Series sends “[Header] OVER [Delimiter]” to the PC, and clears all the
data stored in the transmission buffer. In this case, the BL-600 Series will stop
operation. Operation is resumed when the BL-600 Series receives a “PASS” in
response to “[Header] OVER [Delimiter].”
LASER ON OK/NG TIM ING
TE ST
BL -60 0
Read data
LA SE R O N OK/N G TIMING
TEST
BL- 600
Read data
Response
(PASS, RTRY)