What is the difference between field instruments with and without the HART protocol?
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May I ask what is the difference between field instruments that transmit 4–20mA signals to the DCS and those that come equipped with HART technology? 1. Currently, there are several field rotameters with remote transmission capabilities; what is the difference between those that do not have HART technology and those that do? 2. Additionally, in electromagnetic flowmeters, the signal output is specified as “4~20mA, active”. What does that mean? Thank you
HART is a communication protocol; parameters can be adjusted using a handheld operator, and instruments with the HART protocol are more intelligent. These rotameter flow meters with remote transmission do not have HART functionality; they simply send signals to the DCS. It’s also impossible to use a handheld communicator to set the range of these rotameter flow meters. The active version of the electromagnetic flowmeter requires an external 220V AC power supply.
Thank you. So, if I want to reset the range of the rotameter, do I need to remove the meter in order to do that? Also, why are the measurement ranges of rotameters typically 50~500 or 70~700, rather than 0~500?
Measurements within this range are relatively accurate, while those in other ranges provide only approximate values. The approximate value cannot be used as a reference for production
1. The range, medium, and other parameters of rotameter are generally fixed; having HART functionality serves no purpose. 2. The range ratio of rotameters is generally 10:1, so it does not start from 0. 3. “4~20mA, active” means that a power supply is required, and it is a four-wire system. 4. Doesn’t toluene seem to conduct electricity?
Another advantage of HART communication is that both digital and analog signals can be transmitted to the control room. Since our factory is also selecting instruments, I encountered the same issue; this answer was provided by the instrument manufacturer. Additionally, it seems that HART communication allows for the direct adjustment of the parameters of field transmitters in the control room. I would like to ask: if the pipe diameter is DN100, is it feasible to use a thermoresistor with an insertion depth of 100 as well?
I would like to ask for advice on this: if the pipe diameter is DN100, is it feasible to use a thermistor with an insertion depth of 100 as well? Generally, such a long insertion depth isn’t necessary; it’s sufficient if it’s just a little over half of the pipe’s diameter.
Choosing 100 might be too short, as you also need to weld the thermistor nozzle, and the length of that nozzle is around 100
It depends on whether it’s a straight connector or a 45-degree connector – the lengths are different. If it’s a flange connection, the lengths are also different, so it depends on the situation
:Lol, what does “4~20mA, active” mean in terms of signal output for electromagnetic flowmeters? It means that once the flowmeter is in operation (after 220V power is supplied and it has been configured), the measurement circuit is closed, allowing a 4~20mA current to be generated; no additional 24V power supply from a DCS or other display device is required. The explanations from those above all seem a bit odd, don’t they? ! This post was last edited by zxg.wylton on 2007-8-24 15:15]
What is the difference between the Hart protocol and the BRAIN protocol?