Data Output Tnc -> Ext; Data Input Ext -> Tnc - HEIDENHAIN TNC 415 Technical Manual

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
+
RTS
–
+
CTS
–
+
TxD
–
Start
+
RxD
–
+ 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
+
RTS
–
+
CTS
–
+
TxD
–
+
RxD
–
Start
+ Positive voltage level
– negative voltage level
8-22 TNC 407/TNC 415/TNC 425
Receiving
buffer full
Data
Receiving
buffer full
2 TNC data interfaces
Data Data
EXT
+
CTS
–
+
RTS
–
+
RxD
–
+
TxD
–
EXT
+
CTS
–
+
RTS
–
+
RxD
–
+
TxD
–
01.98