Fully Integrated I/O Solutions
Low-cost, High-density I/O Eliminates Breakout Boards and Signal Conditioning
Most I/O products on the market come in one of two varieties. They are generally either designed for factory floor automation or for general-purpose lab use. The factory floor I/O products typically come configured as robust, flexible plug-in modules that have pretty good functionality, but the modules tend to be quite large and very expensive. The general-purpose lab I/O products are usually configured as relatively low-cost and compact plug-in cards but they have comparatively little functionality, signal conditioning, protection or power. Because of this they require custom break-out boards, signal conditioning and solid-state relays to be useful in machine automation projects. Of course, this means they lose their size and cost advantage very quickly.
ControlPoint I/O solutions offer the best of both worlds. ControlPoint I/O offers high-power, flexible outputs and unique Digilog™ analog/digital inputs with programmable thresholds and hysteresis, for $6 to $13 per I/O point. These solutions are small (0.4 to 0.8 cubic inches per I/O point), can be distributed around a machine where convenient, and require no break-out boards or signal conditioning, thus saving significant cost, design time and sourcing effort. Better still, they use the same common driver software as all the other ControlPoint products meaning that the coordination of I/O with machine motion and other functions is simple and reliable.
ControlPoint I/O products consist of the IOC-540 I/O Cluster and the IEX-808 I/O Expansion Module. The IOC-540 is a node on the ControlPoint network that provides 10 Digilog inputs and 6 high-power outputs. The IEX-808 Expansion Module provides 8 digital inputs and 8 moderate power outputs in a very small, low-cost package that expands the capability of an IOC-540. Up to four IEX-808 modules can be daisy-chained off of one IOC-540. With these two products, a single ControlPoint network can accommodate thousands of versatile I/O points without requiring breakout boards or special signal conditioning.
IOC-540 I/O Cluster Node
Inputs
The IOC-540 is a truly unique I/O product. Its 10 inputs are Teknic's exclusive Digilog™ inputs. They are analog inputs with programmable high and low logic thresholds. This allows them to be used as digital or analog inputs, and when they're used as digital inputs, the actual signal level can be read in addition to the logic level. This allows the user, for example, to tell when there is dust on an optical sensor and perform preventative maintenance. Programmable input filtering and edge detection (rising or falling) further increases the usefulness of these inputs. Edge detection and latching input registers avoid the loss of transient events, and the filtering (and programmable hysteresis) prevents spurious responses to noise and provides for debounce of electro-mechanical switches.
The inputs can be set up to automatically send interrupts to the host CPU so that no polling is required, thus the application software can be notified whenever inputs have changed. Furthermore, the inputs can be fed into an on-board Programmable Logic Array so that any logical combination of inputs, in any polarity, can also generate an interrupt (and/or change the state of the outputs). These features greatly increase system responsiveness without over-burdening the host CPU.
In addition to programmable thresholds, hysteresis, filters and edge latching, the IOC-540 inputs have a number of features to allow for easy, flexible and low-cost integration into automated machinery. Each input pin is supplied with its own separate ground pin and +5 and +12 volt courtesy power. The inputs can safely handle 24 volt devices, and are protected against ESD, surges, over-voltage and negative voltage. The input connectors were chosen to allow easy, semi-automated cable assembly, and they cannot be accidentally interchanged with the output connectors.
Outputs
The IOC-540's outputs were engineered to allow machine designers the ability to connect directly to almost any device used in automated machinery without the need for breakout boards, relays or extra circuitry. Each output can support a continuous load of up to half an amp (500 mA) at 24 volts. Each output is optically isolated from the others as well as from the inputs to reduce the chance of transmitting noise throughout the machine or creating ground loops. For maximum flexibility, each output can be individually configured for either current sinking or sourcing.
An active clamping circuit dependably protects each output from voltage spikes caused by switching inductive loads. Each output is short-circuit protected, overload protected, and reverse-voltage protected, making them extremely robust and reliable, both during machine assembly (when most wiring-related failures occur) and in the field. The IOC-540's output power capacity along with its independent optical isolation, inductive load handling, sink/source capability, and rugged protection, makes it more functional than a bank of expensive solid-state relays (and a lot less expensive).
For convenience and ease of integration, each output has a separate ground pin and +24 volt pin. A pair of daisy-chain connectors allow for easy routing of 24 volt power between all IOC-540's in a machine. When using the outputs for logic functions, their unique "hybrid-Darlington" configuration allows the low output state to go to near-zero volts, unlike most high-power outputs. This provides additional noise immunity.
In addition to normal software control of the outputs, each output can be automatically actuated by the IOC-540's Programmable Logic Array (PLA). Every 256 microseconds, the PLA executes a user-defined logic expression, consisting of logical combinations of its inputs along with a general-purpose timer and feedback terms. Any or all of the outputs can be actuated via the PLA. This allows for very fast output responses to complex situations without any host CPU overhead. The PLA can also automatically interrupt the host, if desired, in addition to changing the output state.
Other software features include a programmable power-up state that allows machines to power-up in a known-safe configuration. A watchdog timer can also be set to ensure that the machine defaults to a safe state in the event of a software application or operating system crash, or upon loss of network communication.
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- IOC-540 Block Diagram
IEX-808 I/O Expansion Module
The IEX-808 allows designers to expand the capability of each IOC-540 by up to an additional 32 inputs and 32 outputs (in four, 8-in/8-out, increments). The IEX-808 is specially designed for maximum I/O density at minimum cost. It packs 8 digital inputs and 8 power outputs into a footprint smaller than a credit card, at a cost of only about $6 per I/O point.
But don't let the IEX-808's small size and cost fool you. Although it doesn't have all the advanced features of the IOC-540, like the Digilog inputs and PLA, it's still quite capable. All inputs are digitally filtered and have latching positive/negative edge detection to reliably capture transient events. The inputs can be configured to automatically generate host interrupts, as well. They're also fully protected and can be connected directly to 24 volt devices without requiring a breakout board.
The outputs can continuously deliver 250 mAmps at 24 volts, so they can handle most solenoids and actuators without requiring additional power circuitry. The outputs are fully isolated from the inputs to avoid noise and ground loops. Furthermore, they are overload protected and have protection to allow direct connection to inductive loads without fear of damage.
Comparison Between the IOC-540 and IEX-808 I/O Products
| IOC-540 | IEX-808 | |
|---|---|---|
| # Inputs/Outputs | 10/6 | 8/8 |
| Input Type | Digilog™ (analog inputs with adjustable thresholding and hysteresis) | Digital |
| Input Filtering | Yes, adjustable | Yes, fixed |
| Transition Detection | Yes, rising and falling edges | Yes, rising and falling edges |
| PLA Capability | Yes, any or all inputs can be mapped to any or all outputs via a programmable logic equation (evaluated every 256 microseconds) | No |
| Output Type and Power | Source or sink, 500 mA continuous | Sink, 250 mA continuous |
| Isolation | Outputs are all individually isolated; inputs share a ground, but are isolated from outputs | Inputs are isolated from outputs |
| Sensor/Actuator Power and Connections | 5V, 12V on-board sensor power; connectors for daisy-chaining external 24V power. Each input pin has its own 5V and 12V pin; each output pin has its own 24V pin. Each I/O pin has its own ground pin. | Connectors for daisy-chaining external 24V power. Each input pin and each output pin has its own 24V and ground pin. |
| Indicator LEDs | Available in RPE software display only ("soft" LEDs). | Individual hardware LEDs for each input and output. |
| Size and I/O Density | 4.99" x 3.62" x 0.70" 0.79 in3 per I/O point | 2.86" x 2.08" x 1.00" 0.37 in3 per I/O point |
| ControlPoint Compatibility | Full | Requires one IOC-540 host per four IEX-808 modules |
| Typical Cost | $13 per I/O point or less | $6 per I/O point or less |