In today’s highly automated machines, fieldbus valve manifolds are replacing conventional hardwired solutions. They more easily perform vital functions by integrating communication interfaces to pneumatic valve manifolds with input/output (I/O) capabilities. This allows programmable logic controllers (PLCs) to more efficiently turn valves on and off and to channel I/O data from sensors, lights, relays, individual valves, or other I/O devices via various industrial networks. The resulting integrated control packages can also be optimised to allow diagnostic benefits not previously available.
However, there are five critical factors that must be considered before selecting pneumatic fieldbus valve manifolds.
Following installation, fieldbus manifolds must be tested and commissioned. When many connections are involved, time and costs quickly add up and users need to look for opportunities to reduce these costs. For example, some manufacturers now offer SPEEDCON M12 connectors, which need only a half-turn to gain a secure connection, reducing commissioning costs. Buyers should also look for well-spaced I/O layouts as these minimise the time needed to connect all necessary cables.
While connections are tedious, configuration can be worse with the prime reason being the dreaded DIP switch. Manipulating these tiny switches is an exercise in frustration. The user must constantly consult cryptic instructions in unfriendly user manuals to identify each switch’s function and settings. Visual feedback is limited to subtle positioning of the switch itself.
A recent innovation is the introduction of pneumatic fieldbus valve manifolds that actually embed a small graphic display on each module. This offers plain-language messaging that clearly identifies network addresses, baud rates, and other parametric data. Pushbuttons enable navigation through intuitive menus and users receive instant visual feedback of set values with error proof selections. This simple system represents a revolution in pneumatic fieldbus manifold interfaces, enabling control engineers to simplify and greatly speed up complex operations.
2. Distribution: flexibility enables savings
Historically, conventional pneumatic fieldbus valve manifolds with integrated I/O modules have been designed within a relatively rigid architecture.
Dedicated fieldbus I/O modules would handle either valves or I/O — one or the other, but not both. So the OEM engineer would specify different modules for each task. He or she would also install multiple dedicated communication nodes on the machine’s industrial network - each having high hardware and associated commissioning expenses.
However, newer designs offer more flexible, significantly more cost-effective architectures. These provide fieldbus nodes that can handle valves and I/O as well as the mutual distribution of I/O and valve manifold functionality around a given machine. Therefore, this allows a large number of I/O distribution options that optimise the physical layout of the machine while using only a few basic multifunctional modules.
Optimising distribution lets the user lower network hardware investment, save time, and decrease the number of nodes on the network - thus optimising network traffic and enhancing topology opportunities for network and power distribution.
These new systems take advantage of sub-bus technology that allows the same modules that traditionally were part of a centralised manifold to be detached and used in a distributed architecture. Perhaps more importantly, on industrial Ethernet applications, this architecture enables a reduction in the number of Ethernet switches and communication nodes. This directly decreases overall cost and system complexity.
For instance, a conventional design might require the use of four pneumatic fieldbus valve manifolds arranged with four EtherNet/IP network nodes. Instead, users should look for a system that allows optimal distribution. The user specifies only one main EtherNet/IP pneumatic fieldbus valve manifold, along with three sub-bus manifolds. Each sub-bus module is a lower cost than an EtherNet/IP module, and requires no costly commissioning. In this example, the costs could be as much as 22% below those for a system requiring four conventional EtherNet/IP fieldbus manifolds.
Thus, new distribution designs offer the potential for substantial reductions in the combined costs of hardware, commissioning, and inventory. They can also accommodate and optimise various machine topology and application requirements.
3. Modularity: allows easy assembly
Traditional fieldbus valve manifolds suffer from a fairly low degree of modularity. This presents challenges for OEMs and end users alike.
For instance, testing or usage may indicate that a particular I/O module is malfunctioning, or a late change order during assembly may require making an alteration. Conventional non-modular designs force the user to dismantle the entire assembly to get access, dismount the offending module, replace it, and then reassemble the whole fieldbus manifold or system.
By contrast, some new fieldbus manifold systems offer modular designs that simply connect together via easily removable clips and screws. This allows easy assembly and effortless last-minute changes for OEMs.
In another example, a user may wish to move the valve modules closer to the valves or cylinders they will be operating. With the new modular designs, the user simply unclips the module from the main pneumatic fieldbus valve manifold and positions it on the machine within reach of the user point and connects it back to the main I/O module via a sub-bus cable. All without disrupting the I/O mapping.
For the end user, modularity permits quick, trouble-free field changes. I/O modules can be removed and replaced without forcing the user to dismantle the entire pneumatic fieldbus valve manifold system. Further flexibility is provided by allowing the same module to be used in either centralised or distributed applications, reducing inventory requirements.