AI810 and HART
We have xa800 system ver 6.03.
We have a number of flow meters that come in on different AI810 cards.
We were going to use HART for these signals.
Is it possible to use the AI810 and HART or must we replace it with AI815?
regards / almen
Voted best answer
Unfortunately, even though ABB designed I/O cards with HART support, they did not add functionality to the 800xA system to enable the HART variables from an instrument to be read into directly into the system at the controller level. In order to get the data back into the controller, you would need to read the values into the system over the 4-20mA through the controller and up into the Connect Server using the HART Device Aspect Objects where it would be available at the console level as a OPC piece of data. From there, you would need to write the OPC value back down to the controller. This approach is a bit cumbersome and does add time delays. This may not be a big deal for slow moving loops like temperature and perhaps pH, but you may not want to do it for things like flow or pressure loops that react more quickly.
The other approach, which is probably cleaner given that it sounds like you do not have that many HART values to read into the system, would be to use something like a Rosemount 333 HART Tri-Loop Signal Converter or a Moore Industries HART Interface Module (HIM) or a Pepperl & Fuchs HART Interface Unit. These devices allow you to bring in a single 4-20mA Input and then strip out the 4-20mA Signal plus other HART values. These values can then be wired directly into the AC800M controller via the AnalogInput module, like an AI810. The one thing here is that if you use one of these HART Interface modules, as they include a HART modem, then you cannot use the AI815 or AI845 Analog Input modules because they also include a HART Modem and the two HART modems on the same line conflict with one another, this the reason that you would simply use a standard AI810.
The thing that I have never understood is if ABB developed these I/O cards with HARD modems, why they did not add the functionality to bring the HART values into the controllers, which is where they would be used 95% to 99% of the time. The odd thing is this functionality is available in the other ABB systems like Freelance and the Symphony Plus system. These also allow for Profibus values to be read in and used at the controller level as well.
Anyway, this is what we have needed to do in the past to read in HART values into the 800xA system from instrument products, including the ABB 266 series transmitters, the Contract actuators, the ABB pH analyzers, etc.
I hope that this information is of use.