I/O

I/O, I/O, it’s show control you know…

I/O is a very straightforward concept. There are inputs and there are outputs. The show controllers from Alcorn McBride support local and remote I/O devices over both network and serial connections.

Inputs allow you to take a voltage or contact closure signal and use that to make decisions. It could be used as a Trigger to start a sequence, it could be used as a variable or parameter in an event, or as part of conditional logic to check if a particular input is ON or HIGH, OFF, or LOW. The controllers support up from 5 to 24VDC on the inputs, with a maximum of 5 mA of current. Alternately, contact closures require no voltage at all. These can be configured on the inputs page. If we apply 24VDC to a voltage configured input, we can see the input turn ON or go HIGH. If we remove the voltage, we see it turns OFF or goes LOW.

The outputs on the controller are dry contact relays. No voltage is supplied by them, but they are capable of supporting DC voltage up to a maximum of 900mA before the polymer-fuses will disconnect the relay’s output (don’t worry, they’re self-healing as long as you don’t abuse them).

The RidePlayer has two Analog inputs; one is an internal measure of the power supply’s input voltage (useful when designing systems that rely on supercapacitors or batteries and the power supply voltage may drop lower than needed to continue operating safely) and a single 0-10VDC input for external use for measuring some relative value in a system. These two voltages are read into the system as Decimal variables for analysis instead of Booleans.

I/O don’t have to be built into the controller’s chassis – sometimes it makes sense for those I/O points to be many feet away. Sometimes it may be in a completely separate building or scene. This I/O can be connected via a network, but it’s treated very similarly inside WinScript. The only difference is that I have to add a device to make them visible and when I address them, I address them as Device I/O in the dropdowns.

I/O isn’t the most exciting part of show control, but the ability to read inputs from an environment and to affect it in return is what show control’s all about, making I/O a necessary and useful part of that system.