I/O (input/output) is very useful for expanding the functionality of digital servo drives. Inputs and outputs can be used to send signals between servo drives or between a servo drive and another piece of equipment without use of a network.
Digital programmable outputs can be configured to activate for specific events such as in-position, at-velocity, over-speed, inhibit, enable, and many more.
Digital programmable inputs can be configured to control the drive for specific events such as inhibit positive limit switch, negative limit switch, etc. Analog I/O can be programmed with specific scaling related to certain events.
Indexing and Sequencing.
Outputs can be programmed into digital servo drive sequences, sending out a signal between indexed steps.
Inputs, on the other hand, can be used to initiate sequences or indexes in a servo drive.
These two aspects can be used together to trigger one servo drive's motion control from another's. We'll discuss this more in our ball toss example.
I/O Example 1: Filling Vials
One customer for ADVANCED Motion Controls was manufacturing a laboratory device where vials were moved along a conveyor-like track and a dispenser filled them with liquid.
When the vials reached the correct position underneath the dispenser, the servo drive would output a signal for the dispenser to release the liquid.
By using our programmable limit switch to control the I/O, we eliminate the need for any timing algorithms and ensure that there won't be spillage if a jam or some other force prevented the track from moving.
I/O Example 2: The Ball Toss Demo
Here's a more elaborate (but arguably more fun) example. If you've visited our booth at a trade show since 2018, you've more than likely seen our 5 Ball Toss demo. Five balls are tossed in the air through spinning rings in various routines. With the five linear motors for the ball launchers and the five rotary motors for the rings, it's a 10-axis system. However, only the launcher servo drives are tied together over a network. The ring drives each communicate with their corresponding launcher drive using I/O.
If you watch the video, you might notice that the rings don't always spin the same way. Sometimes they do quick double spins, sometimes they flip back and forth, and sometimes they do slow single spins (see all three from 0:42 to 0:56). Each one of these spins requires different timing with the ball's launch, otherwise impacts will occur.
To avoid impacts, there are three different sequences built into the launcher drives, each one containing output signals that are sent out in designated times in the launch. The ring drives then receive these signals as inputs that trigger different indexed spin moves, ensuring the timing is always correct.
This greatly simplifies the setup process for us. We don't have to worry about the individual timing of the ring drives when writing the routines for the overall display since they will always be synchronous with their launchers. It allows us and our Click&Move® controller to treat it as a 5-axis system instead of a 10-axis system.
- Programmable I/O greatly expands the flexibility of a servo drive and can be a handy tool for system designers
- I/O can be configured for Active High or Active Low to match the logic of connected devices
- DigiFlex® Performance™ and FlexPro® drives have multiple programmable digital and analog I/O that can be configured for over 60 events and signals