Addition or elimination of I/O in a project is unavoidable. During the process, a switch may be replaced by a transmitter or addition of skid may happen. The sudden change in the system to house a few additional I/O points and processor with spare capacity has to be identified to accommodate the same. In the case of greater I/Os, splitting of controller happens, which leads to reconfiguration of process equipment to new controller and the Herculean task of physically moving I/O cards. This may cause delays or increase the panel spacing.
Electronic marshalling was introduced to make the process of field cabling simpler and decrease the time and labor involved in such activities.
Following are the challenges faced in marshalling:
- Complex process of device integration and replacement
- Time consuming, error prone and labor intense
- High cabling, planning, and documentation costs
- Large footprints and multiple cabinets
Different products and protocols involve costly inventories and trainings
Most of the distributed control use closed protocol for communication. Ever since the introduction of Industrial IoT (IIoT), there is push for open network automation solutions in all the products. Understanding the demand from the market, Siemens launched its first-ever electronic marshalling solution that works on an open industrial network. The products, SIMATIC Compact Field Unit (CFU) and SIMATIC ET 200SP High Availability (HA), use the recognized open architecture industrial Ethernet protocol for communications and standard redundant PROFINET.
SIMATIC Compact Field Unit (CFU):
It is a compact unit installed at process level and connected using PROFINET to the control system. Use of digital fieldbus communication over conventional 4-20mA technology aids in easier integration of device to the system. Each 16 I/O CFU module supports 8 channels of PROFIBUS PA.The SIMATIC CFU verifies the communication profile of the field device pre-defined during engineering of the field device. The installation time is reduced from half an hour or more to less than a minute when compared to manual integration. Along with LED diagnostics, SIM ATIC CFU also features predictive diagnostic functions which continuously provide information. It enables 30% reduction in cabling and 70% less terminations.
SIMATIC ET 200SP HA:
This device reduces footprint in the control panels. To eliminate engineering, assembly, and wiring costs, the device is enabled fixed wiring and push-in terminals. It has redundant PROFINET connection with controllers via copper or fiber-optic cables. SIMATIC ET 200SP HA is designed to also be used in hazardous areas up to zone 2-22 with a temperature range of -40 to 70 °C with conformal coating of all components. The modules are hot swappable with wide range of I/O modules, such as 16×AI / 8×AO HART, 16×DI, 16×DO, etc.
General Station Description (GSD) standard:
GSD files comprise of description of the PROFIBUS DP/PA or PROFINET devices and enable automatically fetching the device characteristics from any device manufacturer supporting PROFIBUS DP/PA or PROFINET open standards. It allows auto configuration of devices during the system engineering phase and minimize the commissioning time. Ethernet physical layer is used instead of a proprietary control network protocol. The Simatic CFU initiates the addressing based on the type of device used and standard profiles
Frost & Sullivan research shows that Siemens has taken the concept of electronic marshalling based on open standard protocols and transformed it to be in line with the latest industry trends, such as Industry 4.0 and IIoT. Automatic addressing and Ethernet-based open standard communication enables the integration of different components available in the market, including remote I/O, drives, and network components. It reduces the commissioning time to a minute when compared to an hour in the case of conventional I/Os. Frost & Sullivan believes that electronic marshalling with open standard architecture is definitely a door to next-generation automation and these products will be welcomed by most of the end users.