No matter what the requirements are, a standard design can be adapted to all requirements. From simple connection between the field and the control system, through measurement signal conversion or electrical isolation, all the way to applications with increased safety requirements such as functional safety or electrical explosion protection.
Comparison of topologies
Standard I/O system
The disciplines of signal marshalling and interface technology have evolved over time to provide the link between field signals and control systems. This covers a wide range of requirements such as: ensuring electrical explosion protection, signal conditioning with relays or signal conditioners, surge protection, and easy connection between the field and the control room.
In classic signal marshalling, the field signals arrive in any order and are sorted according to their signal type. The marshalling level is wired to the interface level, which in turn is wired to the I/O level. Here, recurring problems in terms of specification, operation, maintenance, and cost arise due to the complexity of signal marshalling. Other characteristics of a classic marshalling approach include:
- Rigid system structures
- Frequent project delays due to extensive planning and significant installation and startup effort
- Increasing total costs due to project delays
- No flexible reaction to changes possible
- Design dependencies
Universal I/O system
The implementation of a Universal I/O system is becoming increasingly common as the industry moves to more customized and demand-driven production processes. The Universal I/O system addresses this trend. These requirements include the following elements:
With Universal Remote Cabinets, the need for large marshalling and interface cabinets is eliminated. Adapting a modular design has not only eliminated some components entirely, but has also made the necessary components more compact so they fit in a smaller cabinet. An improved build density reduces the number of cabinets required, resulting in less hardware, installation, and weight.
Pre-engineered and tested Universal Remote Cabinets are easy to install in the field, close to the process. Then, all that needs to be done is to connect the field wiring to the marshalling system and the power supply and the communication lines to the control system. All important components are located in these control boxes. This makes maintenance and troubleshooting so much easier.
In the planning phase, there is no need to differentiate between individual I/O signals, as software can be used to adapt the individual I/O channels to the required function. Universal I/O cards thus open up the possibility of adapting each channel individually.
Universal I/O supports the planning and implementation of signal routing. This allows planning based on the total number of I/Os, where individual functions initially play no role. The I/Os can be adapted via software later in the project. This reduces project and life cycle costs compared to the standard I/O system.
Intelligence shifts to the field
With Universal Remote Cabinets, the need for large marshalling and interface cabinets is eliminated. The field signals are marshalled and processed directly in the cabinets. The connection to the Universal I/O system is then made using the system cable. The final connection to the control system is established via a single fiberglass cable.
Comparison of process automation projects Universal I/O versus Dedicated I/O
The Universal I/O concept, in combination with intelligent signal marshalling, offers significant advantages for planning and implementing complex process automation projects. Project information that was previously required at an early stage, such as the number of individual field signal types, is now only required at a later stage of the project. This makes planning and procurement simpler. In addition, individual project steps can be processed in parallel due to the increased flexibility of the approach. Overall, this shortens project lead times significantly, which also reduces total investment costs.
Existing problems of a Universal I/O system:
The required interface technology is missing, such as:
- Relay for signal conditioning to the I/Os configured as digital output
- Interface modules with intrinsic safety type of protection
- Signal isolator for separating ground loops
- Elimination of signal distortions
VIP I/O marshalling as a suitable solution from Phoenix Contact
- Provides the same flexibility at the interface and marshalling level
- Is designed for the use of Universal I/O systems
- Consists of three blocks to meet the requirements at the interface and marshalling level:
o The base element attached to the standard DIN rail accommodates the field wiring and provides the connection to the I/O system via connectors
o The Input-Output Accessory (IOA) fulfills the actual interface function
o A system cable connects the base element with the Universal I/O system
- Offers the right interface for every requirement