Wavetronix Click 500 (programmable controller) (CLK-500) - Developer Guide - Manual (Page 19)

18 CHAPTER 1 • USING THE CLICK 500
Warning
If you are developing an application that uses the front DB-9 connector as a normal
serial port, the Click 500 will not work until it is in run mode. The debugger uses this
port in program mode and the device will have to be changed to run mode to test the
operation of this port. Instead of constantly toggling the switch between run and
program mode, consider using a second serial cable with pin 4 removed. Insert/re-
move the second serial cable with pin 4 removed between the normal serial cable and
the front DB-9 connector. With the second cable in place, the device will essentially
remain in run mode when power is cycled (even though the switch is ON).
Using Digital I/O
The digital I/O ports on the bottom of the module allow you to interact with contact closure
and digital I/O systems.
Digital Outputs
The digital outputs are simply solid state contact closure outputs. Each digital output port
is completely independent of the other port. A digital I/O port communicates either open
(0) or closed (1).
Note
The logical 0 or 1 is in reference to the software value written by the microprocessor.
When the O1+ and O1- pins are connected to each other, the interface is closed and desig-
nated by a logical 1; when the O1+ and O1- pin are NOT connected, the interface is open
and designated by a logical 0. This also applies to O2+ and O2- pins on the second digital
output port (see Figure 1.7).