Citizen Systems CLP-621 - Manual (Page 53)

53
Appendixes
Interfaces
XON/XOFF Protocol
Requirements to output X-ON code
• Communication is possible when the power is on.
• When the receive buffer has less than 128 byte available, XOFF code is
output, then the receive buffer has at least at least 1024 bytes available.
Requirements to output the X-OFF code
• When the receive buffer has less than 128 bytes available
16Kbyte
XON
XOFF
Receive buffer
1024 byte
128byte
DTR Protocol
Conditions when the DTR signal is “Ready (High)”
All the following conditions are satisfied.
• The receive buffer is 128 byte or more available capacity.
* When the receive buffer has less than 128 byte available and the DTR
signal has changed to BUSY (Low) status, BUSY status is maintained until
the capacity of the receive buffer has reached 1024 bytes or more.
Conditions when DTR signal is “Busy (Low)”
• When the receive buffer has fallen to less than 128 byte available.