Integrating Environmental and Production Data
In most production environments, it is critical to be able to associate historical environmental data with process data to
demonstrate that the environment was within specification during batch and lot production and storage. This can be accomplished
in many ways. Three of the five integration approaches described above would be acceptable solutions (field bus instrumentation
integration, ELCPI integration, or database integration), but which one is most effective?
Many owners use the field bus instrumentation integration solution because it is simple and fairly dependable. However, utilizing
two sensors and sending the data from one sensor to the PCS for monitoring and records retention and the data from the other
sensor to the BMS for control is expensive when you consider the cost of the industrial sensors and transmitters required
and the lifecycle and operational cost associated with keeping two sets of sensors calibrated and maintained. Using one sensor
and a qualified splitter that sends the data to the BMS for control and the PCS for monitoring and records retention is a
more cost-effective solution, but remember that the splitter must be calibrated per your standard operating procedures.
The ELCPI option involves passing critical data between the BMS and PCS workstations via a common protocol. Since it usually
happens that a common protocol does not exist, this integration requires a protocol converter or integration device. The integration
device is simply an industrial PC that houses software drivers for both the BMS and the PCS protocols. The PCS and the BMS
are connected to each side of the PC, typically via a serial connection. The integration device tables the data on both sides,
enabling data exchange.
Finally, one could go to the top level of the architecture and use an integrated database. This differs from the previous
approach because each system gathers and stores its own data before bringing it together. This can be very tricky because
it requires organizing both databases identically. In most cases, one of the databases (most likely the PCS database) is assigned
as the master database and data from the subservient database data is queried, copied, and imported into the master database
via a reporting tool. Alternatively, that system can input its data directly into the master database, eliminating the subservient
database and eliminating the steps involved in combining the data. The only disadvantage could arise if you need to separate
the data for any reason.
Despite these issues, ELPCI integration can be the most effective solution for tying environmental data to lot and batch production
data. Once this method of data transfer is set up correctly and properly tested, it is typically a reliable solution with
a low cost of ownership.
Depending on how critical the environment is to the production process, the production line may need to be shut down if the
environment goes outside of the control parameters. Production of a bulk powder product open to the environment during one
or more production steps is an example. In this case the temperature and, more importantly, humidity are critical to keeping
the product granular and avoiding clumping. In this example, the BMS can be set up to direct alarms to many locations including
- production operator's or manager's email account
- production operator's or manager's pager
- traffic light alarm enunciator
- directly to the PCS (for warning or shutdown depending on criticality).
The first three options can all be handled by a BMS's alarm-management software. The last option requires one of the following
integration strategies: field bus controller integration, supervisory controller integration, or ELPCI integration.
Depending on the process protocol, field bus controller integration can be unreliable. This would be the most efficient way
to handle the integration (since the data would not have to travel up the BMS network, only to be sent back down the process
network), but the availability of efficient integration tools is limited. In most cases, a gateway device would be required
to make this work.