Remote I/O for Distilleries

The old automation system in the VAT house consisted of three ITT PLC systems, with conventional wiring via barriers to the hazardous area. Irish Distillers have previous experience of utilizing fieldbus with Profibus DP and PA networks installed elsewhere on the site, and so it was not surprising that it was decided to utilize Fieldbus in this upgrade.

DeviceNet was selected for use with Motor Control Stations, and Profibus DP for communication of all field automation signals. Irish Distillers selected Turck’s Excom Profibus DP for zone 1 hazardous areas as the best solution for the interface of the automation signals. Turck excom systems were supplied by Turck’s Irish Distributors Tektron, based in Cork, Ireland, who also provided technical advice to the project.

High channel density and hot swap

Mick McCarthy, IDL E&I Manager for this project, selected excom over other Hazardous area remote I/O vendors, “due to the high density that can be achieved in the MT18 module rack. The hot swap functionality also impressed us, as we can now remove and fit all modules during ongoing operation – without having to interrupt fieldbus communication.” Another benefit: the automatic adjustment of power from the DO40Ex digital output card use this single type of I/O card for all Digital Output cards thereby reducing specification and design engineering.

The ease of implementing full communication and power redundancy was an obvious factor. IDL have chosen to utilize communications redundancy from the outset. However, they have not implemented power redundancy for the present and see that it is a big advantage that they can implement power redundancy simply by fitting an additional power supply to the MT18 rack.

LED indication for every device on the rack was another feature which led to excom being selected. The Turck stainless steel field panels have a viewing window to allow the operator or maintenance engineer see the status of a card or channel without opening the door.

The project size was in the region of 800 I/O, with the integration works carried out by Rockwell Engineering, Cork, using an Allen Bradley PLC. The Project required 12 new excom remote I/O stations (MT18). To ensure the maximum speed available (1.5 MBaud) could be achieved,
four Turck SC12Ex segment couplers were used, providing four sets of redundant intrinsically safe Profibus segments in the field, which allowed the design engineers ensure that the maximum Profibus DP cable length was less than 200 m. The Remote I/O panel locations were selected to ensure good distribution and that instrument cable lengths were kept to a minimum.

The VAT house is an important part of the distillery process. It was critical that as much of the installation work and in-fact testing and commissioning be carried out before disconnecting the existing system. This was easier to implement due to the use of excom remote I/O panels as the new automation cabling could be installed without obstructing production.