Enabling and Setting a ccOutputLine

You must enable your output line before using any other function on it:

oline.enable(true);

To set the output line high, use the set() function:

oline.set(true); // sets the line high
oline.set(false); // sets the line low

Invoking set(true) has different effects on TTL and opto-isolated lines:
For TTL output and bidirectional lines, set(true) sets the TTL high state (+5 V)
For opto-isolated lines, set(true) enables the no-current-flowing state (the LED inside the opto-isolator is OFF, and thus the circuit is open and not transmitting a signal through the opto-isolator)

The meanings of set(false) are as follows:

For TTL output and bidirectional lines, set(false) sets the TTL low state (0 V)
For opto-isolated lines, set(false) enables the current-flowing state (the LED inside the opto-isolator is ON, thus the circuit is closed and is transmitting a signal through the opto-isolator)