There is an acknowledged requirement for all companies to satisfy the constant pressures to increase operational efficiency, reduce costs and maintain

HMI (human machine interface) devices report faults in automation systems either automatically as system diagnostics (with no configuration and no cost implication in SIMATIC solutions) or via manual intervention. However, with an estimated 80% of faults during any operation process related, and the fact that diagnostics are plant-specific and cannot be integrated into the controller resulting in programming needs and increased cost – the role of diagnostic tools in helping to alleviate ever-spiralling overheads, as well as keeping plants running and available has never been more important.

Conventionally, process diagnostic functions are programmed separately from the actual control programme. In addition to this convention, appropriate error messages alerting operators to faults must be displayed on the display equipment. The associated programme code work can easily be as extensive - and expensive - as the overall control functions themselves and if the control programme is modified in any way, this also results in the monitoring functions having to be reprogrammed.

With management scrutiny on expenditure at all times – especially in the tough economic conditions being currently experienced in many economies - the potential outlay exposure in the process area can be considerably reduced using a range of simple diagnostics tools. The tools when specified offer a number of clear advantages for implementation and operation alike:

Easy wins include simplified configuration and automatic change management. Here process diagnostic tools through SIMATIC are configured in one step when the automation control solution is programmed. Variables are monitored and marked and the error state defined and a comment assigned to it. Likewise any monitoring functions are automatically updated when the control functions are modified

With a need to keep maintenance budgets under control pre-emptive fault finding can be a real asset in a process operating environment. Again, diagnostic tools can help in the key areas of troubleshooting and preventative work.

When a fault occurs, implementing a user-friendly criteria analysis enables the precise criteria in the network or the logical operation that resulted in the error to be displayed. For such a criteria analysis a programming device is not required. It is performed on the HMI device and this accelerates error detection and rectification drastically. Likewise in the area of preventive maintenance, disturbances in the process sequence can be detected at an early stage and interpreted by operational personnel. This means that faults are prevented and instances such as tool wearing - which is indicated by increasing frictional forces - are quickly identified and rectified before a small issue becomes a major problem. Process diagnostics tools can monitor such frictional forces and action taken to rectify the situation – usually at a much lower cost.

Remote Control

Machines and plants are increasingly operated in places which are far removed geographically from the place of manufacture. Plant constructors must nonetheless be able to provide support in the event of a fault. Here, developments in remote maintenance and remote link via services such as telephone cable based TeleService can make significant contributions to the smooth running of process plants through remote diagnosis, value setting and data transmission from any location back to a central operator point. Service call occurances can be drastically and resulting travel and personnel costs slashed through such implementation.

For remote maintenance, a designated operator can simply dial into a remote plant by telephone and read status information or to correct the user programme remotely. The remote connection is used to transmit data via the telephone network and three types of remote connection are achievable including: remote connection to a plant which is initiated by a programming device or PC, for example to transmit recipes to a remote plant or to transmit process or plant files for analysis or processing at a central office; remote connection to a PG or PC initiated by the plant or remote connection between two plants for exchanging process data. The remote and user friendly capability lies in the ability to send text messages from plant to a mobile phone or to a provider for onward communication via a fax or e-mail.

It is clear that there is a constant need to work smarter. Available technology through some of the diagnostic tools outlined here help in this objective, saving time and money in many cases with monitoring, fault-finding, preventative maintenance strategies and remote control all now easily within the reach of plant operating personnel.