The setup involves rosemount 3420 fieldbus interface module & rosemount 848T temperature transmitter. The update rate as mentioned in the product data sheet of 3420Model for One AI Block is around 0.3 seconds, whereas i am getting update rate of 8 seconds per AI block.
Necessary Blocks are only Enabled in 848T transmitter. Can anyone tell me where I went wrong?

 

You will probably not receive an answer to your questions on this forum. Your best bet will be to contact your local Rosemount salesperson... they will be able to help you.

BR,
Roley

 

Please check the quality of cable you have used. Class A is the latest and recommanded cable. Can you brief on fieldbus hook-up? so i can tell you more.

Sachin

 

The cable-integrity game is the standard Rosemount line. Next they will be telling you that your grounding isn't correct. I have been involved in an extensive DeltaV/ Foundation fieldbus installation where this was the company line. It always, in every case, ended up being a programming problem or deficiency in the controller. While it is possible that cabling is your problem (really, how hard is it to get the cabling right anyway?)from my experience you need to look elsewhere. If you are using DeltaV, it is likely that this is as fast as that system will go. The job that I was on had Rosemount distributor programmers on-site. They always tried to blame problems on the cabling/grounding (which was flawless) but the next thing you know, after hours of hacking around with that limited software, they would come down from the programming station (or whatever they called that $20,000 Win NT 4.0 obsolescence) and announce that the problem was mysteriously gone. Also in the same plant, on a job that I wasn’t directly involved with, The programmers were using devicenet to control pump and other process motors, again with DeltaV and supposedly the eminent programmers from the aforementioned distributor. When the operator would press the start or stop buttons in the field, the action would be delayed by approximately 5 seconds. This, as far as I know, is still the case at that plant today. (2-1/2 years later)

Could it be a flaw in DeltaV? I'm not overly familiar with the nuts-and-bolts of DeltaV but these results seem undesirable. The moral of this rather long-winded story is that DeltaV, and Foundation fieldbus, in application, appear to be rather slow.

 

Please check the Scheduled Macrocycle and the Required Macrocycle for the Modules. Refer Books Online for the same.

In fieldbus the H1 Card is the Link Master and it has its own scan time in addtion to module scan time; where it polls the devices connected to it... something like that...

So, just make sure if the FF Segment is designed properly and the Macrocycles are set properly. Please revert if required.

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