Work with a 4-20mA signal or preferably SPI data using MCP3008 or similar

[walkuf]

I built my system with (2) IFM Magnetic-inductive flow meter SM6x04 or SM6004 that have a 4-20 mA outputs for Volumetric Flow and Temperature. I purchased a 4-20mA to 1-10V converter module and a 1-10V to Frequency converter module and am pretty sure I didn't damage my RPi. They all seem to work however I think they lack a zero crossing or other criteria for CBPi4-Flowmeter to pick them up. What are the current pulse input signal requirements? Is 0 to 1.2V at 500Hz good? That's what I think I may have. I have an oscilloscope coming to confirm what my signal looks like.

I'm sure a lot of error is built into this solution and I'd like to develop the current flowmeter plugin to accept a Voltage input device. My thought was to convert it to a voltage and use an MCP3008 chip to input the data through the SPI interface. Does anyone know how to modify this code to use SPI data? I like the protection that the MCP3008 offers the RPi. Plus you can add multiple channels this way for several devices.

Thanks,
Rick