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Ethernet I/O Simplifies Wave Solder Machine Control
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ules, including analog, digital, count- er module, an 8-channel solid state relay (SSR) module board, and a 16- channel SSR board. All current wave soldering, reflow soldering, and cleaning models built by Electrovert use the model 2600 Ethernet based I/O. Calvo explains: “The 2600 series
and the cost of additional enclosures for these modules can add quickly and was not called for. Many other electronic manufac-
turing system designs employ a two- piece electrical interface. In such an approach, one interface board, com- patible with low-voltage computer
Individual function modules.
was designed around how the prod- uct would be used in our machine, based on collaboration on design, fit, and function.” He added: “Sensoray worked with us on a plug-and-play concept. The end result was a design that took the interface out of the computer and put it out in the ma- chine close to the motors and heaters.” The design strategy included
detailed discussions between Senso- ray and Electrovert’s engineering group to examine the pros and cons of the existing design. Electrovert then developed a “wish list” of fea- tures for the new generation of I/O. The two companies then sketched out a rough draft of a next-genera- tion system design. Electrovert’s systems are used
in demanding production environ- ments in competitive markets, and are designed for durability. High-vol- ume production environments re- quire systems that run constantly, with minimal downtime. Customers for these systems require reliability, and Sensoray designed the I/O for op- timum system-level reliability. For example, the model 2600
Series systems use DIN-rail-mount- able open-frame modules that quick- ly snap onto standard 35mm DIN rails without need of screws or bolts. When an electronic cabinet is built on the side of a machine, all of its electronic components are placed in a NEMA enclosure except for the con- trol computer. To simplify assembly, Sensoray screws DIN rails and bolts onto the back side of the system box. During final assembly, the 2600 modules are snapped onto the DIN rail. If a module fails, operators can unsnap the module from the rail, snap in a new one, and be back in business. Sensoray opted not to put the
DIN-rail-mountable modules in its own enclosures. Since the feed lines are protected inside a NEMA enclo- sure, the designers felt there was no need for an additional enclosure. As many as 10 to 12 modules are includ- ed in each wave soldering machine,
signal levels, plugs into a computer. The other interface board connects to equipment that controls motors, lights, and temperature sensors using a termination board. A cable connects the two interface boards. In contrast, the model 2600 is a single- board solution. Field wiring can con- nect function modules directly to I/O boards, eliminating the need for ex- ternal termination boards and reduc- ing material and assembly costs. The original “wish list” for this
next-generation wave soldering sys- tem included a quadrature output with the capability to sense direction and higher-resolution analog inputs for more precise and accurate control of temperature. With the model 2600, the electronics are mounted outside of the machine. Short cables are used since the electrical interface is located next to the machine in- stead of at the other end of the sys- tem, greatly simplifying cabling re- quirements as well as manufacturing costs and serviceability. The Ethernet-based I/O design
provides a number of key benefits, including performance enhance- ments and shorter distances from electrical interfaces to modules. As an example, signals run from tem- perature sensors inside the machine module are subject to distortion from electrical noise, with impact on measurement accuracy. By locating the electrical interface closer to the modules, shorter communications wires can be used to the module, with less chance for distortion from elec- trical noise.
The New Standard While developing the model
2600 product for Electrovert, a key consideration involved selecting a way of connecting to the interface board that would protect the design from obsolescence through the bus. Equipment manufacturers must con- stantly deal with the threat of obso- lescence, where host platforms have a limited life expectancy. When Electrovert originally
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