I understand all the theoretical differences between a PAC and PLC, but have yet to actually compare their operation in an industrial setting. PACs advertise they have the stability and reliablility of a PLC, but with superior programming techniques (such as LabVIEW). I am trying to determine whether to use an Allen-Bradley PLC or PAC in an embedded control system, which will consist of a 3rd party device which will send/receive data with a PAC or PLC via Ethernet. The PLC/PAC will process the data and send to a PC for display on an HMI. This system is required to run for months or years at a time (ignoring the periodic reboot of the PC) without fail, and while PACs claim they can reach the same level of stability as a traditional PLC, I don't have any experience with them and can't make that assurance to our client. We have processing software for the 3rd party device written in LabVIEW, so it would be nice to use a FieldPoint PAC.
I'm hoping someone with experience using a PAC can share some of their knowledge. Is a PAC as stable as a PLC? Can a PAC, if properly programmed, be stable and run for months or years at a time? Are there any problems or other considerations I should be aware of?
Any information at all will be appreciated, thanks very much.
A very good question and one that has many dimensions, my experience with PAC controllers is as follows.
I am a longterm (>15 year) Labview developer and believer.
My first experience with NI PACs has been excellent.
I have had my first PAC controller in continuous production operation for the last 18 months with no reliability problems in either hardware or software. If properly programmed they seem to be every bit as solid and reliable as a Rockwell Automation (Allen Bradely) PLC.
The main argument for PLC's over NI PAC's is related to the extremely large PLC support industry that already exists.
This is primarily due to the large installed base of PLC's used by large manufacturers for their plant operations.
Electrical distributors and programming/design consultants for PLC's abound. Kinda like the Verizon Wireless commercial.
Electrical Maintenance departments in large manufacturing plants are generally more familiar with the care and feeding of mainstream PLCs
On the pricing side NI PAC system hardware is about 60% of the cost of an equivalent PLC system for larger systems.
PLC programming while an established skill and technique for sequential manufacturing automation, it is not nearly as capable and powerful as Labview for handing and analysing data from all types of instrumentation.
I also think that Labview MMI's generally look more professional and display scientific data better with much less effort/cost than PLC equivalents.
For the application as stated, I would say do it with an NI PAC. You will not be sorry.
For the record, I am not an NI employee, nor do I own any NI stock.
I hope you find this helpful.