Overview
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Industrial control and monitoring applications utilize a variety of high-density connection techniques to interface the field devices with the control elements (PLC's, Rack Mount I/O, Industrial Computers, etc.). One way to accomplish this is to plug a cable with a high-density connector directly into the control system. The other end of this cable then must be pigtailed to facilitate the discrete wiring of individual field devices. As you can imagine, this complicates system wiring, and can be a time consuming, unreliable, and error prone method.
The preferred method of interfacing devices of this type is to use the same high-density connector on both the control and field ends of this cable (instead of pigtails). This field side connector can then be plugged into a pre-assembled modular unit that is designed for discrete wire terminations. This is the basic idea behind Phoenix Contact's VARIOFACE family. VARIOFACE is a variable wiring technique that has the ability to standardize device connections, and organize them into a fast, compact, and modular way of integrating components into a system.
Fundamental characteristics of all VARIOFACE modules are their ability to be mounted on standard DIN-rail, to have compact terminal strips, and to have clear identification of devices and circuits, and maintain a modular and adaptable design. The capabilities of the VARIOFACE solution are unmatched thanks in part to the sheer breadth of the products available from the PCB terminal block line. discrete wires can be terminated in thousands of configurations using a screw clamp, a spring cage, crimp contacts, or even Insulation Displacement Connection (IDC) terminals. These distinctions allow the VARIOFACE solution to enhance any system's design with respect to planning, assembly, start-up, modifications, field wiring, and troubleshooting.
Some examples of the control equipment with which VARIOFACE modules are most commonly used are as follows:
- PLC's - Programmable Logic Controller - Industrial computers that can accept different input and output modules. PLC's were designed to replace the necessary sequential relay circuits used for industrial control. The PLC works by scanning its inputs and depending upon their state, initiates its outputs either on or off. The user enters a program, usually via software, that contains the functional programming.
- SCADA - Supervisory Control and Data Acquisition - An industrial measurement and monitoring system. SCADA systems rely on a variety of communications systems, and typically exhibit open-loop control characteristics (no feedback or corrective capability).
- DCS - Distributed Control System - A DCS system is a package of dedicated hardware along with supervision and process control software. Communications are typically via a LAN (local area network), and DCS systems usually employ significant amounts of closed-loop control (controlled variables are compared to set points, and can be corrected).
- Motion Controllers - Devices used to control the motion axes of various drives and motors
- CNC -Computerized Numerically Controlled machine - Used in the machine tool industry. CNC lathes and machining centers allow variables such as feed, speed, and depth-of-cut to be programmed and stored.
Of course, the high-density connectors used with these devices vary. But with VARIOFACE, any connection (D-Sub, HD-Sub or Ribbon Cable just to name a few) can be interfaced with a pre-assembled, modular unit.
Individual VARIOFACE modules are also offered in a variety of configurations, and the designs are categorized under four basic subheadings:
Passive modules
Passive modules (also referred to as standard breakout terminals) connect discrete wires point-to-point with a range of high-density connectors. They are available either with or without LED indication of signals. Passive modules are packaged in several housing types that offer the designer space savings and functionality that is compatible with the application's requirements.
Active modules
Active modules connect discrete wiring with active control devices such as electromechanical and solid-state relays. These modules are available in different configurations for input connection styles and on-board electronic devices.
Device Specific modules
Device specific modules refer the types of modules that are specifically designed around the use of a certain type of device. The types of devices that would typically be used such a module would be 3-wire sensor and actuators. Using this type of module would offer the benefits of eliminating unneeded terminal blocks and increased space savings. Control panels can decrease in size by using less equipment inside therefore, increasing the savings on construction of the panel.
Solution Based modules
Solution based modules are created for customer specific applications. Applications may require the solution to also be a proprietary item. In this case the modules can be custom printed and boxed to the customers specifications. For most any applications that would be presented, there would be an acceptable solution in a DIN-rail mountable module to reduce the customer's inventory and increase productivity.
