Siemens SIMATIC TIWAY 1 - Manual (Page 81)

THE TIWAY I NETWORK PORTS
UNILINK HOST ADAPTER 4–7
USER MANUAL
You also have a choice of using either NRZ or NRZI encoding with the modem
interface. NRZI is recommended because of its self-clocking properties.
A special Clear-to-send (CTS) to transmit timing delay has been provided for
use with radio link modems, ranging from 0 ms to 1,000 ms in 10 ms increments.
There is also an RTS/CTS timeout. These delay values are set through
configuration commands described in Chapter 2 and Chapter 5.
4.1.3 Runaway Transmitter Recovery
The UNILINK Host Adapter is equipped with a timeout or runaway
transmitter recovery mechanism which ensures that the transmitter does not
remain turned on longer than twice the time required to send the maximum
length message. If the transmission exceeds this limit, the adapter will perform
a hardware reset, discarding all macro buffers and any outstanding directives.
NOTE
The hardware reset restores the adapter to the
initialized or power-up state. At this point, the
adapter will have to be reconfigured and the network
restored to its operating state.