HEIDENHAIN TNC 335 Technical Manual - Manual (Page 530)

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TNC 360 2 TNC data interfaces 8-23
Hardware handshaking
Bit 2 can be set to determine whether the TNC stops transfer from an external device by using RTS.
– Data output TNC -> EXT
When the receiving buffer is full, the external device resets the RTS signal. The TNC thereby
detects that the peripheral unit receiving buffer is full because of the CTS input.
TNC EXT
–
RTS
+
–
CTS
+
–
TxD
+
–
RxD
+
–
CTS
+
–
RTS
+
–
RxD
+
–
TxD
+
Receiving
buffer full
Data Data Data
Start
+ Positive voltage level
– Negative voltage level
– Data input EXT -> TNC
When the receiving buffer is full, the TNC removes the RTS signal, which is detected by the
peripheral device at its CTS input.
TNC EXT
+ Positive voltage level
– negative voltage level
–
CTS
+
–
RTS
+
–
RTS
+
–
CTS
+
Receiving
buffer full
–
RxD
+
–
TxD
+
Start
–
TxD
+
–
RxD
+
The DTR and DSR signals from the TNC indicate the operational status of the TNC and peripheral
(these cannot be set via the machine parameters).