To use or not to use.......

Being in Instrumentation/Control maintenance, I have often debated within myself if I would like to use more and more soft communication interface or stick to our beloved, age-old, conventional hardwired 4-20 ma system. Project and Engineering guys- pardon me if I am more inclined to the conventional system.

If I consider Capex, deployment of more and more soft communication interfaces,will bring down the cost and duration of big-basket, I/O intensive projects fulfilling the aspirations of the Design & Project Engineers. After a few years of commissioning, when the design and project Engineers get busy with their next project,it is the hapless maintenance Engineer who has to run fom pillar to post to identify the fault within a minimum downtime adhering to a shoestring budget and time-line for spare procurement.

On the other hand, the conventional hardwired system is very easy to trouble-shoot. There is no delicate electronics and therefore no obsolescence, no ageing effect(considering the life of a plant to be 30 years and assuming no fire hazard),leading to a very low maintenance cost. No highly paid expert is required for the maintenance.

In this respect, I am not aware if any one has attempted the cost analysis of gain in the capex vis-a-vis the loss in the opex over the life-time of a plant. The point of concern should be profit in the long run of the business and use high-end technology if it augments that.

It may appear that I a'm biased with the conventional system.But I'm not.In the MIS level of the hierarchy, engage as many as possible soft transactions for generation of meanigful data or optimization. For the sake of simplicity, the basic control data acquisition may be spared from "bus" and "traffic".