User Manual

Operation
RFI-9256 Radio Modem User Manual Page 35 of 96
Network link always functions the same way on the slave unit, regardless of protocol mode. On a slave
network link comes on whenever the slave has successfully locked with a master radio and is hopping with
it. It will be turned off after the time specified 2 * network link timeout (ms) passes without the slave
receiving its master's transmission.
When a serial port output (DCD or CTS) has been configured to follow online or follow network link, the
output will be high so long as online or network link is red or green. Once online or network link goes black
the serial port output will go low.
4.4 Auxiliary I/O
The RFI-9256 supplies 8 auxiliary digital I/Os (+5V TTL) that can be mirrored across a radio network. Each
digital I/O can be individually configured as an input or output, and digital outputs can have a default state
when power is applied before a connection is established to a remote radio (see appendix B.4.2 for details).
4.4.1 Input Sampling
All digital inputs are sampled at a fixed interval that may also be configured. The smaller the sample interval
the faster changes will be propagated across the radio network. However if a lot of changes occur to the
digital I/Os in rapid succession this can generate a large amount of traffic that may adversely affect serial
port data throughput.
4.4.2 I/O Routing
I/Os are routed transparently on point-to-point or Hayes dial-up links. When a point-to-point link is used and
remote I/O is enabled, each output on a unit will be set to the current state of the input on the other unit. For
this reason it is important to ensure that the outputs on one unit are matched with inputs on the other unit.
When Hayes dial-up is used, the I/Os will be mirrored so long as a connection is established. When the
connection is closed the I/Os will be held at the last known value.