CITIZEN CLP-521 - Manual (Page 46)

Appendixes
46
XON/XOFF Protocol
Requirements to output X-ON code
• Communication is possible when the power is on.
• When the receive buffer has less than 2K byte available, XOFF code is
output, then the receive buffer has at least at least 4K bytes available.
Requirements to output the X-OFF code
• When the receive buffer has less than 2K bytes available
XON XOFF
Receive buffer 16kB
2kB 4kB
DTR Protocol
Conditions when the DTR signal is “Ready (High)”
All the following conditions are satisfied.
• The receive buffer is 2K byte or more available capacity.
* When the receive buffer has less than 2K 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 4 Kbytes or more.
Conditions when DTR signal is “Busy (Low)”
• When the receive buffer has fallen to less than 2K byte available.
Interfaces