Tait T2000-A75, Руководство по эксплуатации, Страница: 16 / 38

16 M2256-000-00-051 November 2001
CTS (Clear to Send) Handshaking
CTS is an active high output signal from the A75 to the PC and is used to prevent data over-
flow under certain conditions such as a full input buffer. CTS should always be used if the PC
and A75 baud is higher than the over-air baud.
If the data throughput rate is small enough (less than 40 bytes in one transmission), then inde-
pendent of the baud, CTS handshaking is not necessary. If the data throughput is greater than
40 bytes in one transmission, CTS must be used to avoid data loss. This assumes a short lead in
delay otherwise the output data will overflow. At a low baud, 300 ms is a short Lead In Delay
but a higher baud may need a Lead In Delay as low as 40 ms.
The CTS state is controlled using bit 6 of the [ITEM1] parameter in the PROGRAM command
which sets up the configuration of the A75.
If ‘Inhibit CTS Signal’ is set to ‘1’, then the CTS signal from the A75 is always on ( CTS hand-
shaking off ).
If ‘Inhibit CTS Signal’ is set to ‘0’, CTS deactivates under the following conditions
• during the Lead In Delay
• if the PTT is pressed
• if the input buffer exceeds 34 bytes from a total 50 byte input buffer
If the PC terminal application continues to send data while the CTS line is off, the data will con-
tinue to be stored in the 50 byte input buffer.
When the buffer is full, further incoming data is lost until there is room in the input buffer again.
CTS will turn on again when the buffered data drops below 40 bytes.
At all other times the CTS is ON (high at PC end).
Data Quantity A75 and PC Baud Lead In Delay CTS Handshaking
<40 bytes / transmission 1200 (2400) - 9600 short not required
>40 bytes / transmission 1200 (2400) - 9600 short required