Hello again everybody
I have more newbie questions which I hope you can answer.
I have an old sensor probe unit (a single device) which measures voltage, temperature, and distance. This probe uses serial communications (via usb cable) to send and receive data to a computer. It used to work by user running a C program on their computer and then inputting a hexadecimal string to send to computer’s COM port and then the probe would interpret the hexadecimal string as a request and send back parameter values as hexadecimal string for computer to convert to actual values.
- code 1A2B is request for voltage
- computer writes 1A2B to COM port
- message is transferred to probe
- probe interprets message and sends voltage value as 04A1
- computer receives 04A1 and translates to 1.182 Volts
I would like to get this probe up and running again with a Cobra II board and was wondering which Serial Modules would let me do it and if it would work with probe.
The modules in catalog are:
USB-Serial Module https://www.ghielectronics.com/catalog/product/287
USB-Serial SP Module https://www.ghielectronics.com/catalog/product/437
RS485 Module https://www.ghielectronics.com/catalog/product/479
I will definitely need TX and RX, but don’t think I would need RTS and CTS (I think these two are just for handshaking but the probe does not use handshaking).
Now I cannot remember but I think the probe will maybe need to be powered through the serial connection (maybe up to but no more than 200mA).
USB-Serial Module does not have any 3.3v or 5v pin connections but both USB-Serial SP Module and RS485 Module do have them, so will either of these two be able to supply power to probe or are they only meant for receiving power?
Also, I know that RS485 Module does not have a USB plug, but I do not mind stripping the probe usb cable and connecting wires directly to RS485 Module.
But I know the probe serial cable uses four wires (i think one each for RX, TX GND, but not sure about what forth cable does, maybe power) and the RS485 Module only has three connection slots for wires, so I would not know what to do with the fourth wire?
I know it is probably easier to just buy similar modules for gadgeteer or just use it directly with old computer (code won’t run on windows 7 and I do not have XP anymore) but I would like to get it working with a portable system (not stationary computer) and prefer the nostalgia of using my old probe.
Help much appreciated, thanks.