Is possible to use RS485 to read a CMOS laser sensor?

Hola. I want to use a CMOS laser sensor with an RS485 interface and find out if it is possible to use the RS485 terminal on the 7i96s board to read the sensor values. My goal is to use the laser to measure height and move the Z-axis to a specific initial height on a plasma cutting machine. I consulted Gemini AI, and it indicated that I needed to flash new firmware to enable this function; consequently, I visited the Mesa website and downloaded the hostmot2 file for the 7i96s. Could someone confirm if that hostmot2 file allows me to use the 7i96s's RS485 port in the way I intend? Thank you very much .

I've never attempted it myself, but supposedly it should be possible.
linuxcnc.org/docs/html/drivers/mesa_modbus.html

I have always used an ordinary serial port (such as a USB to RS485 adapter dongle) to communicate with Modbus devices using the MB2Hal driver.

What protocol does the sensor use?

Modbus is supported by Mesa FPGA cards with the hm2-modbus/PktUART
drivers.

If your sensor does not use Modbus, fora Mesa card, it would require
a driver part like hm2-modbus communicating with the PktUART driver


 

Okay, the first option is using the USB adapter, but having a long USB cable is a bit inconvenient for my setup; the electronics are at the back of the machine and the PC is in front, in an external rack. Still, if there's no other way, I don't mind—though I wonder if the reaction time is slower via USB compared to RS485? This matters because it involves the sensor I want to use to measure the plasma's Z-axis. Then again, it might not really matter, since the head doesn't move while measuring the Z-distance; it just measures and calculates, then moves directly to the initial cutting height.

The manual specifies 8-bit asynchronous MODBUS via 2-pin RS-485 (A+ and B-); so, do I need to flash the pktUART driver? That is done by updating the firmware and using terminal commands, right? Gemini AI suggested something along those lines.

Yes, you would use 7i96s_pktv3.bin firmware.
 

If you are using a USB to RS485 adapter you are not running a USB cable to your device. These adapters generally don't have a USB cable at all, and are just a dongle you plug into your computer's USB port. You then run a RS485 cable from there to your device. As to speed, I'm pretty sure USB is quite a bit faster than RS485.

I have previously used 485 dongles but I think the mesa board connection is a cleaner wiring solution. I have used mb2hal but hm2-modbus is much easier for me.

I also found hm2-modbus/mesa refresh to offer much faster refresh than hm2hal/USB dongle which was important with some spindle calculations I was using to calculate gear ratios.

My advise is get the correct firmware and enjoy the cleaner wiring, easier message setup, and faster response with the mesa connection.