1, Dalin Communication basic judgments
The faults of a fieldbus communication system may mainly come from three aspects: the communication master station, the connection line, and the communication slave station. In the elimination process of the actual communication fault, the three aspects of isolation judgment can quickly and accurately find the fault.
In the actual process, the same or similar equipment can be used to replace the master station, segment or change the connection line, reduce or cross-replace the slave station and other methods to effectively eliminate the fault.
2, GSD file and master station parameter setting
In the communication master station, the correct GSD file should be installed first. As the Profibus Association and Danfoss update their products, Danfoss will update its GSD file on its website. If the GSD file version used by the user is more than The VLT inverter software version is old, which may make it impossible for the master station to drive the VLT inverter.
At the same time, the corresponding parameters should be set on the main station side, such as data format, communication rate, etc., and the main point is to set the mapping address of the slave station equipment, although most of the master station equipment (such as Siemens S7-300) All the addresses can be assigned automatically, but mapping address conflicts may be caused when frequent additions, deletions of slaves, or manual operations are performed.
3, how to determine the communication quality of Danfoss inverter
With an RS232-RS485 converter and dedicated Danfoss test software, an effective connection between Profibus and PC can be established
The test software can be used to search Danfoss equipment in the Profibus network, use different data formats to communicate and control the inverter, and check the communication quality (error rate) during the communication process. Through the testing of this method, the user can basically judge Danfoss frequency converter's Prpofibus communication function is perfect.
4. Influence of EMC on Communication Lines
Because the inverter products are high-interference components, interference is a common cause of poor communication in practical applications. The communication cables and power cables are routed separately, using standard Profibus cable connections and a good shielding layer grounding is the most effective way to eliminate electromagnetic interference. Good method, but many users did not pay enough attention to this point, we recommend two grounding in the ground network system with good potential conditions (see the figure below).
5, parameter P512
The setting of the Danfoss frequency converter parameter P512 (taking the VLT5000 as an example) affects almost all types of bus communications. P512 is mainly for the use of control words, its options ProfiDrive and Profibus protocol does not have a corresponding relationship between the user can not fully understand the meaning of the case, we recommend the use of FC options (factory settings).
6, other
Profibus communication of some Danfoss products (such as MCD3000 soft start period, etc.) uses a gateway product provided by a third party. The use of such a gateway is slightly complicated and cannot be tested by the aforementioned test software. When using the product, refer to the related product use. Instructions.