This document has been edited to remove any confidential information
The Project.
To appraise the existing UV reporting system at an undisclosed wastewater treatment plant.
Recommend actions necessary to provide a simple reliable reporting system.
Shortcomings of the current system
We have received a great deal of anecdotal evidence as to the failings of this system and it is difficult to sort the wheat from the chaff.
We have had all sorts of failure causes suggested, the favourite being that the 'black boxes' get too hot, but we found the temperature of these units reasonable.
There is no doubt however that the system is unreliable (and may have always been so) and even if we had access to software source listings and circuit designs, correcting the faults may not be economically possible. There is also a risk that this approach could be a 'dead end' technically.
We also know that serial comms systems can be noise sensitive, influenced by cable length and type, and can get 'out of step' (synchronisation). This may well explain the most often reported fault i.e. If a module is "polled" after being taken offline for cleaning, the module fails to communicate and drops offline resulting in erroneous information to the SCADA.
We can see no effective way to correct or improve the current system; even the people who built it have never been able to make it reliable.
We could waste a great deal of time and effort on an abortive attempt to come to terms with this system.
Outline of Current System.
It is in our opinion unnecessarily complex.
The current system is a mixture of RS 422, RS 232 and MODBUS serial software at both ends of the comms chain.
Overview of
Control panel 
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