Eco Physics CLD 780 TR - Page 110

E C O P H Y S I C S RS-232 interface
CLD 780 TR / July 2000 107
8.3.3 Examples
a) Valid data transfer
Host CLD 780 TR
(Master) (Slave)
→
→→
→
STX, Address, Command,...Data..., ETX, BCC
→
→→
→
←
←←
←
ACK, Error code, ETX
←
←←
←
or
←
←←
←
ACK, Error code, STX,...Data..., ETX, BCC
←
←←
←
b) Transmission errors
The host sends a command to the CLD 780 TR which receives the message
corrupted and responds with a negative acknowledge.
The host repeats the message. The second trial is successful.
Host CLD 780 TR
(Master) (Slave)
→
→→
→
STX, Address, Command,...Data..., ETX, BCC
→
→→
→
←
←←
←
NAK, Error code, ETX
←
←←
←
Repeat
→
→→
→
STX, Address, Command,...Data..., ETX, BCC
→
→→
→
←
←←
←
ACK, Error code, ETX
←
←←
←
or
←
←←
←
ACK, Error code, STX,...Data..., ETX, BCC
←
←←
←