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Giới thiệu giao thức HART
The HART (Highway Addressable Remote Transducer) protocol uses the Bell 202 Frequency Shift Keying (FSK) standard to superimpose digital communication signals on the 4-20 mA loop current shown as below figure. HART communicates at 1200 bps without interrupting and interference with the 4-20mA signal and allows a host application (master) to send/receive digital information from a smart field device. The 4-20mA signal communicates the primary measured value – the fastest and most reliable industry standard. The digital signal can be used for additional device information including device status, diagnostics, additional measured or calculated values, etc. Therefore, the HART communication including analog and digital information provides a low-cost and very robust complete field communication solution that is easy to use and configure.
HART is a master/slave protocol which provides for up to two masters (primary and secondary) and the secondary master such as handheld can be used to monitor/control the informatoin of HART bus. HART can be used in various modes such as point-to-point or multi-drop for communicating information to/from smart field instruments and central control or monitoring systems. The following are the description of two main HART operation modes.
(1) Peer-to-Peer mode (analog/digital)
The analog and digital information can be communicated simultaneously in this mode. Both the 4-20 mA current and the digital signal are valid output values from HART instrument. The polling address of the HART instrument must set to be “0” and just one HART instrument can be put on HART bus. An optional “burst” communication mode where a single slave device can continuously broadcast a standard HART reply message can be used in peer-to-peer configuration and the higher update rates are possible.
(2) Multi-drop mode (digital)
In this mode, only the digital signal can be used and the analog loop current is fixed at 4 mA. It is possible to have up to 15 instruments on HART bus. The polling addresses of the instruments could be from 1 to 15 and each instrument needs a unique address.
Feature:
- Relatively easy to understand and use, the HART protocol provides access to the wealth of additional information (variables, diagnostics, calibration, etc.)
- HART is a no risk solution for enhanced field communication
- Compatibility with standard 4-20mA wiring
- Simultaneous transmission of digital data
- Risk reduction through a highly accurate and robust protocol
- Increase Plant Availability
- Reduce Maintenance Costs
- Improve regulatory compliance
HDS (HART Device Simulator)
HART Device Simulator (called HDS) is the HART device simulation software developed by ICP DAS. It can be used to simulate multi HART slave devices simultaneously to exchange data with HART master device by using ICP DAS HART converter (like: I-7567 / I-7570 / I-7547) connected to any COM port (USB / 232 / 485 / Ethernet). By this way, users can develop or verify the HART master program without any HART slave device.
Applications
Features
- Free HART slave device simulation software (must work with any ICP DAS converter: I-7567 / I-7570 / I-7547)
- Support more than twenty HART commands (like: CMD0 / 1 / 2 / 3 …)
- Provide the setting for the long frame address of HART device
- Provide the setting for the value and unit of HART command 3
- Support 16 HART devices simulation simultaneously (address 0 ~ 15)
- Exchange data with HART master device by using ICP DAS HART converter (like: I-7567 / I-7570 / I-7547)
- Support HART communication data log
- Compatible with revision 5 and 6 of HART protocol
- When the COM port is open, the HDS will listen for the incoming requests and response data
- Only the HART simulation device with the “Enabled” option checked will response data
- The field of the “Short Frame Address” is fixed
- The field of the “Long Frame Address” with 5 bytes can be set to simulate the different HART manufacturer’s slave device
- All the HART communication data can be logged to file
- The four main values and units of PV / SV / TV /QV of HART command 3 can be set for every HART simulation device.
Converter, gateway and remote I/O modules HART
The following are the HART products provided by ICP DAS including converter, gateway and remote I/O modules etc.
Model | Type | Description | |
---|---|---|---|
Converter | I-7547 | Ethernet(TCP/IP) to HART converter | Remote to acquire HART information and send/receive HART command via Ethernet |
I-7567 | USB to HART converter | Convenient for users to acquire HART information quickly and send/receive HART command via USB | |
I-7570 | Serial to HART converter | Easily integrate HART devices via serial port including RS-232 / 422 / 485 interface with HMI / PLC / PC | |
HRT-227CS | HART to Fiber converter | Extend HART communication distance via single mode Fiber Optic medium (30 km) | |
Gateway | HRT-310 | Modbus RTU/ASCII to HART Gateway (Upright) | Designed as the HART master device and allows MB/RTU & ASCII master to access the HART devices |
HRT-310-UTA | Modbus RTU/ASCII to HART Gateway (Upright) | Designed as the HART master device and allows MB/RTU & ASCII master to access the HART devices (for -40 ℃ application) | |
HRT-710 | Modbus/RTU & ASCII to HART gateway | Designed as the HART master device and allows MB/RTU & ASCII master to access the HART devices | |
HRT-710-UTA | Modbus/RTU & ASCII to HART gateway | Designed as the HART master device and allows MB/RTU & ASCII master to access the HART devices (for -40 ℃ application) | |
HRT-711 | Modbus TCP/UDP to HART Gateway | Designed as the HART master device and allows MB/TCP client to access the HART devices | |
HRT-711-UTA | Modbus TCP/UDP to HART Gateway | Designed as the HART master device and allows MB/TCP client to access the HART devices (for -40 ℃ application) | |
GW-7557-B | PROFIBUS to HART gateway | Designed as the HART master device and allows PROFIBUS DP master to access the HART devices(Plastic Case) | |
GW-7557-M | Designed as the HART master device and allows PROFIBUS DP master to access the HART devices(Metal Case) | ||
Remote I/O Unit | I-87H17W-G | HART AI module with 8 ch. for PAC | I-87K module for AI signal acquisition and send/receive HART command |
Filter | HRT-370 | HART Signal Filter (Upright) | Splits the input HART device signal to two output channels. (1)One channel keeps the original HART signal. (2)Another channel filters the HART signal out to output pure analog current signal. |