Citizen CLP-521 User Manual

Appendixes

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