Few process industry cost-cutting initiatives begin at the marshalling cabinet, but a new intelligent marshalling alternative from Invensys may change that.

Thad Frost

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Few process industry cost-cutting initiatives begin at the marshalling cabinet, but a new intelligent marshalling alternative from Invensys may change that. Marshalling cabinets are used to collect field wires from devices throughout the plant. Once connected, these field wires are rerouted to the DCS terminations and the marshalling cabinets serve to keep DCS wiring and field wiring safely segregated.

They do so effectively, but changing signals—say from analog to digital input—traditionally requires rewiring. A more recent design has involved swapping out separate modules for each combination of signals required by a process. Invensys has now introduced a new marshalling alternative in the form of a universal FBM module, an intelligent marshalling product that promises to eliminate the need for marshalling cabinets.

Invensys’s new 247 FBM fits into the standard base plate of its I/A Series DCS and can be programmed with software to manage most standard I/O combinations. Working from a networked I/A Series workstation, a process engineer can configure the module for operation with HART, analog inputs, analog outputs, digital inputs, digital outputs, and any combination, and this has numerous benefits.

Intelligent marshalling lowers equipment costs by reducing footprint requirements and improving I/O density. It also saves field labor, and inventory. Rather than maintaining an inventory of spares to accommodate various combinations, for example, process manufacturers need keep only a small number of these universal modules on hand and can configure them when and where needed.

Minimizing spare inventory is especially valuable in DCS installations that have fixed requirements for maintaining a certain percentage of spares. Such requirements are based on I/O type, such as analog inputs and outputs, digital inputs and outputs, HART inputs and outputs, etc. Because the Invensys intelligent marshalling module is universal in nature, one I/O point on one module can fulfill the requirement for what might otherwise be a costly inventory of spare parts.

Some situations even require “hot spares” modules to be stored and maintained on-site, which can get very expensive, especially where multiple remote cabinets may have been deployed. Intelligent marshalling replaces multiple types of I/O modules for “hot spares” with one universal module that can be configured to manage numerous I/O signal paths.

The I/O points can be configured via software; once wired, the I/O point could be modified from an engineering workstation via Internet, anywhere, with appropriate permissions. Changing an I/O point no longer requires installing a whole new module, opening a cabinet, driving to a remote location, purchasing an airplane ticket, or incurring any of the other costly tasks usually required.

Intelligent marshalling installation also requires fewer cabinet drawings for the construction and maintenance reference.

Intelligent marshalling provides process engineers with a simple and effective way to lower operating costs.

- Thad Frost is manager, research development and engineering, Invensys Operations Management, www.invensys.com. Edited by Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com.