more work than a standard “plug in the cards” backplane bus, it is actually a benefit in many industrial applications. This is because there is no bus to limit or define the voltage, current, type (AC or DC), or total amount of power that can be supplied to the various modules. Further, a defined bus—which has its well- known benefits in embedded systems—would constrain the type and number of highly diverse data channels needed, such as having dozens of analog 4-20 milliamp (mA) loops together with Ethernet data paths, to cite two “extremes” of signal speed and type. The DIN rail has been especially beneficial for power supplies with their wide array of voltage/current ratings and corresponding size and power ratings differences. It offers flexibility and possibilities for all parties: supply vendors, specifiers, and users. Some power supplies and other modules (such as PLCs) are designed specifically for DIN rail, but many can serve both rail and non-rail applications with the addition of a simple, low-cost mounting kit. This is an advantage for supply and module vendors, as it allows offering the same unit in multiple end product form factors; doing so reduces the number of distinct units that need to be built and
stocked, thus simplifying the repair and replacement supply chain and shortening repair and upgrade time. The DIN rail does not define the I/O cable routing for the modules which it holds. However, DIN rail devices such as PLCs, sensor/ actuator interfaces and loops, and other interconnection modules generally have inputs located on the top and outputs on the bottom. Again, since the DIN rail is only a mounting rail, it can accommodate
and two meters or can be custom cut to any desired length which is useful for unique projects. The standard also defines for, but does not mandate, standard cutout slots (called perforations) for ease of attachment to a panel. For example, Altech Corporation offers its CA601/S “top hat” rail measuring 15 mm deep (Figure 3). The rail is available in zinc plated steel, stainless steel, and aluminum in lengths of one and two meters, as well as custom lengths. The rail plus its modules are usually mounted in a rack or equipment cabinet for physical integrity and safety. However, it can also be mounted to a wall or other horizontal surface if it makes more sense in a specific application for visibility and physical access. Vendors also offer a wide array of interconnection terminal blocks, brackets, clips, and other items that facilitate DIN rail use. Also, if perforations are not required, there are options available without them. Note that the DIN rail is just that: a mounting rail and not an interconnection bus, although the rail may provide a chassis grounding connection. The various units mounted via the rail are then interconnected with discrete cables. While this may seem to be less convenient and
specialized situations where the common arrangement is impractical or undesired.
Available modules: a wide assortment Every project has a power supply, and DIN rail supplies are available covering AC and DC inputs with outputs that span low, moderate, and high AC and DC voltages at various power levels. For example, the DRC-5V10W1AZ from Delta Electronics is a basic, single output, fully enclosed AC/DC converter delivering 5 volts at up to 1.5 amperes (A) for a total of 7.5 watts from a package measuring 91 x 56 x 18 mm (Figure 4). This universal input supply operates on voltages ranging from 90 to 264 volts AC, and features Class II, double isolation, so no
we get technical
45
Powered by FlippingBook