GLP compliant system to monitor multiple experimental rigs at an environmental laboratory.
At one of their UK based environmental laboratories, Zeneca run a set of experimental rigs which require constant monitoring and data logging. In order to conform to the standards of GLP (Good Laboratory Practice) and to prove the integrity of the data to their customers, they needed a system which could accurately and regularly record data to a secure location. After careful consideration, Zeneca chose a Prodigy SCADA system as the base for their new laboratory system.
Features and Benefits
Laboratory Alarm and Monitoring System
The system consists of a central supervisory PC computer which monitors a range of analogue and digital inputs and outputs. Signals can be accepted from a wide range of sensors including thermocouples, resistor thermometers, pressure and flow transducers, strain gauges etc. These I/O points are located in outstations in each of the laboratories in which the studies are performed. The outstations have keypads and LCD displays to enable local data viewing and study control.
From the main system computers, the user can choose to see an overview of the whole facility or take a closer look at details of a particular experimental rig. In addition, studies can be prepared and details of the studies in progress can be viewed. Access to these functions on the main computers as well as control functions on the outstations are password controlled ensuring that unauthorised users cannot gain access or tamper with the study data.
The system uses the 21 CFR Part 11 Compliance facility within Prodigy to ensure data integrity, security and traceability. The data is written to CD-ROM to provide a long-term storage medium for high quality archives.
To ensure that the data collected is accurate, the outstations provide easy methods of calibration against known parameters.
The Prodigy system monitors all the analogue and digital inputs. Up to four alarm regions can be associated with each of these inputs and if the value of the input enters this alarm state then an alarm will be activated. The alarms are visible on the main computers and even when accepted recur every 30 minutes until rectified to ensure the problem is dealt with. The alarm system is also connected to the company pager network so that an engineer is contacted and the problem can be resolved quickly, even outside normal working hours. The Prodigy system also controls digital outputs to each test rig, allowing Prodigy to place the rig into a safe static state whilst the alarm condition is resolved.
A necessary feature of the Zeneca project was to ensure that the system was kept running continually with no disturbance. This was required so that the data logging would not be interrupted causing the data to become incomplete. To ensure that failure of the main system computer was not critical, a dual PC arrangement was adopted. The use of a “hot backup” system means that if the primary computer fails then the secondary computer will take over the data logging. In normal operation, data is recorded automatically to the hard disc drive of both the primary and secondary computers. In addition, the secondary computer uses a CD writer to archive the data for long term storage and off-site backups.
To prevent disturbance by power failure, both system computers have a backup power supply and in addition, each outstation has its own battery backup supply. The network is connected by 4 multi-drop serial loops. Communications integrity is maintained by adopting four separate comms links between the outstations and the supervisory computer.
Support and Development
A key feature of support is the use of a modem link from the supervisory computers to the Prodigy system suppliers. This link is controlled by Zeneca to ensure system security. It allows engineers to access both the primary and secondary PC systems as if they were actually on-site. This provides a rapid response at reduced cost resulting from the savings made in travel time and expenses. Annual system maintenance contracts with options for on-site cover and 24-hour help line are also available if required.
One of Zeneca’s key aims for their system was that it should be flexible enough to enable upgrade or future expansion. Prodigy’s modular approach allows the system to be expanded and modified to meet current and future requirements.
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