using a MAX232 for signal conditioning in automotive environment

[Build-A-Burger]

I want to measure the wheel speed of each of 4 tires in a 4wd truck using hall-effect switches and send the signals to my onboard controller. I was thinking of using MAX232 chips to convert the signal to +/- 15v or whatever the RS-232 standard is, and then use another MAX232 chip at the controller to convert it back to TTL. All 4 wheels plus the crank sensor (for RPM) would mean (10) MAX232 chips plus all the supporting caps and resistors. Is there an easier way to boost the signal to avoid loss of the signal due to stray EMF?

 

[Surendhar M]

Its a suggestion more than a solution to your question. As it is the signal conditioning its better to carry the signals with the shielded cable and also if possible carry with differential signals method (RS485)

 

[ravindragudi]

In the present day, there are lot of other methods available and being practiced by auto industry to transfer the sensor info from node to ECU. The proven and reliable method is to use CAN bus transmission of the sensor data. It is not only for Txing sensor data but also helps in diagnosis, fault handling and monitoring/ controlling sensor node operations.
Even if you dont want to use CAN signalling, you should be using frequency of the 3.3V/ 5V signal instead of relying on the signal amplitude itself. This is a standard practice on speed detection sensors. You can refer to some speed sensor modules for auto industry.