Echelon I/O Model Reference for Smart Transceivers and Neuron Chips - Manual (Page 28)

18 Introduction
The IO2 pin is an output bit I/O object (because the output is declared last).
Assuming that the io_set_direction( ) function is not called, a subsequent call to
the io_out( ) function for ioPoint2 sets the level of this pin. A call to the io_in( )
function for ioPoint1 can then be used to read back the actual pin level of this
output object.
Multiplexing I/O Models
Input to one of the timer/counter circuits can be multiplexed among pins IO_4 to
IO_7 or provide output to IO_0. This timer/counter is called Timer/Counter 1 or
the multiplexed timer/counter. A second timer/counter circuit derives input only
from IO_4 or provides output to IO_1. This second timer/counter circuit is called
Timer/Counter 2 or the dedicated timer/counter. Figure 6 shows a signal flow
diagram for both the multiplexed and dedicated timer/counter circuits.
Figure 6. Flow Diagram for Timer/Counter Circuits
Performing I/O: Functions and Events
A Neuron C application program can access I/O objects in either of the following
ways:
• By using an explicit io_in( ) or io_out() function
• By referring to an event associated with the object in a when clause
• For timer/counter objects, by using the io_select() function
The following sections describe both methods.
General I/O Functions
After you declare the I/O objects for a Neuron C application, you can access the
objects through the I/O functions that are provided by Neuron C language. Table
7 on page 19 lists these functions. You do not need to declare or link these