In the application of CAN bus pressure sensor, there are many devices that produce electromagnetic signal, including ultrashort wave equipment, audio equipment, power supply, etc. The following measures have been taken:
1) In order to further improve the anti-interference ability of CAN bus pressure sensor nodes and ensure that the CAN bus pressure sensors are completely isolated and independent, tx0 and rx0 of LPC2294 are respectively connected with TXD RXD of tja1050t through high-speed optocoupler 6n137. However, it should be specially noted that the two power supplies used in the optocoupler circuit must be completely isolated, otherwise the use of optocoupler will lose its significance. Low power isolation module b0505s is used for complete isolation of power supply. Although it improves the stability and security of some nodes.
2) Two 120 Ω resistors are added to the two ends of CAN bus pressure sensor, which play an important role in the matching of bus impedance. Removing them will greatly reduce the anti-interference and reliability of data communication, even unable to communicate.
3) There are two 30pf capacitors in parallel between canh and canl of CAN bus pressure sensor and the ground, which can filter out the high frequency interference on the bus and have certain anti electromagnetic radiation ability; a 5.6v TVs tube is incorporated between the two can bus access terminals, which can play a certain role in overvoltage protection through the short circuit of TVs tube when the CAN bus enters voltage interference.
4) In order to reduce the interference to the node, shielded twisted pair is used, and according to practical experience, the shielding layer of shielded cable does not need to be grounded. This article originates from Zetian sensing Please keep the source!
Related product information link: Cyb230-s7 output pressure transmitter