Hi,
I just saw the newslettter with the article about an ROV submersible. Now I have some questions about the communication between remote daq devices and the central computer.
I want to use five DAQ-devices, in a serial arrangement, with about 100 m cable between the single devices. The cable is just plain telephone cable, and the power supply as well as all communication has to go through the cable.
SensorArray#1 - [ 100 m cable - SensorArray#2-5 ] - 100 m cable - Control PC/Power supply.
At each sensor array several values are recorded (pressure, temperature, light intensity, and others, with some with a acquisition rate of at least 3 kHz).
I wonder which is the best, and which is the cheapest way to control these 5 sensor arrays over one cable over a maximum distance of 500 m. I think for CAN the handbook says that 500 m is the limit in thick cables, but telephone cables are quite thin. There is a significant drop in voltages above 500 m, as they have I think 4 Ohm resistence per 100 m.
I was thinking about 5 remote PC/104 computers, which are communicating with the control PC via LAN or serial (RS-485) communication, or with CAN? All the equipment in the arrays has to be powered by power through the cable, so I think there might occur some interference? As I have no background in this kind of cabling/communication, I wonder if somebody here could argue in the one or other direction?
Thanks a lot!
