Comparison of 375 and 275 controllers
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The 375 field communicator is essentially the former ROSEMOUNT 275HART handheld device; after ROSEMOUNT was acquired by EMERSON, it became part of EMERSON’s product line. Its purpose is to allow for direct configuration of instruments that support the HART protocol on-site – tasks such as setting TAG numbers, range settings, and output types – as well as for detecting issues with these instruments (such as performing self-diagnostics or measuring actual pressure levels). It also provides analog output, enabling the transmission of a controlled signal to the control system for testing purposes. It is recommended to read some papers on the HART protocol to gain a better understanding of it. The HART protocol is an internationally standard protocol for instruments, initiated by ROSEMOUNT. It is known that several companies manufacture HART handheld devices, but the most important chips are produced by ROSEMOUNT and are certified. The 375 is better than the original 275; it can now be used to program not only Emerson’s own instruments but also any instruments that use the HART communication protocol. Well-known instrument manufacturers such as KROHNE, ABB, and SIEMENS can also have their instruments programmed using this device. HART375 is a new type of handheld operator developed based on WINDOWS CE, which provides the previous HART275 models and their upgraded versions with a user-friendly interface, as well as features such as easy installation and removal of drivers. At the same time, HART375 not only supports the HART communication protocol; ROSEMOUNT375 also supports the FF bus protocol. The functions that are commonly used on-site include adjusting the range of the table, as well as performing zero-point correction and relocation. For example, in the case of Emerson’s 248 temperature transmitter, if the originally specified range is 0–200 degrees with a PT100 input type, but the actual requirement on-site is 0–800 degrees, then it is possible to modify both the range and the input type using the 375 device. However, the service life of PT100 decreases when it operates above 500 degrees, so its use is not recommended. ‘When an actual temperature range of 0-800 degrees is required on site, it’s not sufficient to simply change the input calibration code; in such cases, a PT100 thermocouple is no longer suitable, and instead a thermocouple with K or E calibration should be used. 1. Purposes of Rosemount 275 and 375 handheld controllers: Operators can use the 275 and 375 handheld controllers to communicate with SWB801, 802G, 1151 pressure transmitters that comply with the HART fieldbus protocol, as well as other devices. The handheld controller is powered by a battery. By connecting 275 and 375 to the transmitter’s signal lines, operators can send and receive information to the transmitter’s memory. Operators can adjust the transmitter parameters and diagnose potential problems either at the control room console or at the field junction box. This method of remote communication reduces maintenance costs and allows operators to configure the transmitters without having to enter dangerous areas. 2. The Rosemount 275 and 375 models have the following functions: ◎ Configuration: It is possible to select operating parameters such as tag numbers, measurement ranges, output types, damping times, and so on. These values can be stored directly in the transmitter’s memory, or they can first be stored in the memory of 275 or 375 before being transferred to the transmitter’s memory. You can choose from ten different engineering units between 275 and 375 as per your requirements, or you can design your own engineering units and program them into 275 and 375. ◎ Diagnosis: It enables the diagnosis of issues related to configuration, communication, transmitters, or the process itself. ◎ Verification: It is possible to verify the transmitter’s output or adjust the zero point for existing process input values. ◎ Display: It can display information from the transmitter or the 275, 375 memory. Put the transmitter in output mode: This allows the transmitter to output a 4–2mA current signal, which can be used for output calibration, fault handling, and circuit verification. Remote adjustment: It is not necessary to be close to the transmitter in order to operate. After the operator connects 275 and 375, he can read the data from the transmitters in the control room, change or reset the transmitters’ ranges, handle faults, and view diagnostic results. Fault handling is fast and easy: 275, 375 – it can perform self-diagnosis of detected issues, and its communication software can automatically alert operators. During communication, the operator can initiate a comprehensive diagnostic check at any time. If a problem is found, detailed information describing the fault condition will be provided. The operator can configure any number of transmitters. If the same data is needed, it can be stored in the memories of 275 and 375, and then retrieved by each transmitter. 3. Use of Rosemount 275 and 375 handheld communicators: Due to the excellent compatibility between our company’s circuit boards and Rosemount’s Smart boards, it is entirely possible to use Rosemount’s 275 and 375 handheld communicators for operation. There are two modes for using the 275 and 375 models of handheld communicators: 1. General mode: This mode is automatically activated once the handheld communicator is connected to the circuit board. In this mode, the main functions of the circuit board can be operated. 2. Borrowing mode: The operational functions of the standard mode are not sufficient; to carry out more operations, we can make use of the handheld communicator to access the functional capabilities of Rosemount’s Smart1151. The method is as follows: in normal mode, set the damping time of the circuit board to 9999 seconds, then power off and restart the handheld communicator; this will bring it into the mode that utilizes the 1151 operation functions. In borrowing mode, the damping time of the circuit board is set to 9999 seconds; by turning off the power and restarting the handheld communicator, it returns to normal mode. Turning off both the circuit board and the handheld communicator, and then restarting them, can also bring it back to the general mode. The circuit board should not remain in the borrowed mode for an extended period; once the operations in borrowed mode are completed, it should be returned to the normal mode promptly.
If practicality is the concern, the 275 seems better; the 375 is too slow. It has more features, but it’s not practical.
The information provided on the 1st floor is great. There is one question: can a laptop be used as a substitute for a handheld controller?
The current 275 models can also communicate with HART instruments from various manufacturers other than ROSEMOUNT. Our unit has two 275 units: one, which is 10 years old, can only communicate with ROSEMOUNT’s HART instruments, while the other, purchased in 2004, can communicate with HART instruments from many different manufacturers (the compatible instrument models from those manufacturers can be seen in its analog mode). The two units look identical; I think it’s likely due to differences in the version of the communication software inside them
A single laptop alone cannot replace the 375/275.
The 375 can also adjust the Rosemount radar and other instruments, and it offers good scalability. It feels slow because there’s too much stuff inside.
With the new version 275, it is possible to use many devices that support the HART protocol, such as FINSHER’s submersible tanks; I’m not used to using version 375 – it’s slow and prone to crashing
If the focus is on maintaining existing instruments, 275 is better. Fast and power-efficient. If it is the installation unit, considering the large variety of instruments to be verified, 375 is a better choice. However, pay attention to the software version and upgrade it in a timely manner.
Modern approaches advocate for versatility; for example, with a PDA, as long as the necessary interfaces and relevant software are available, many functions can be implemented, and there are no major technical challenges. With such a large volume and a price of over 30,000 yuan, it boils down to one thing: monopoly.
It should be possible. The key is to have the HART protocol software and a MODEM. Does anyone have HART software? Please share it!
A HART protocol converter connected to the notebook can replace the handheld operator
The original poster has provided a very thorough analysis of this topic; that’s excellent! However, as an experienced professional in the field of field controllers, I believe that changing 275 to 275 is nothing more than a trick used by EMERSSON to deceive Chinese customers. The main difference lies in price, and it’s just an excuse to raise prices in a disguised manner! In fact, many domestic manufacturers are capable of producing field controllers on their own; the cost involves just a few circuit boards and some programming for communication purposes. The price difference between such controllers and those priced at 275 or 375 is enormous, yet their functions are pretty much the same. This is something I’ve experienced firsthand: take one of the domestic companies’ field controllers as an example – it can be used for communicating with HART protocol smart pressure transmitters, electromagnetic flowmeters, target flowmeters, and vortex flowmeters. It’s compatible with HART275 and HART375, as well as with 1151, 3051, EJA, ABB, and other imported instruments that use the HART protocol. It’s also fully compatible with various domestic smart pressure transmitters. Yet its price is less than 10,000 yuan. Different people have different opinions!
What was said upstairs is correct. It’s just a trick used by manufacturers to make money. In fact, the 275 works very well.
:Lol, our company ordered goods from the United States, and the equipment was sent wrong – an extra pressure regulator and a 375 were included!
Supports 275, 375; prone to crashing
Actually, 275 is not bad, but some of the new instruments cannot communicate, so it’s necessary to keep updating to the latest version
At present, using 375 only involves the most basic operations; functions such as range adjustment and tag assignment are used to a limited extent, and its applications are still quite imperfect. I hope to learn more about related topics