This might be slightly OT for an FPGA group, but maybe someone has run into a similar problem before:
I'd like to connect my FPGA, via JTAG, to my PC, 100m away. Due to a hazardous environment, putting the PC any closer isn't feasible
I'm using a Xilinx parallel cable III, which I extended with RS485 drivers to get to required distance, before converting back to TTL to drive the original cable.
Currently, Impact (correctly) finds the correct number of devices on the JTAG chain on two different boards, but identification fails.
A bit of exploration with a scope shows data flowing pretty much as expected, with a clean wave arriving at the board. Another, rather worrying, aspect is that the transmission delay through the systems is about 800ns - rather a lot on a 200kHz communication system.
Does someone perhaps know whether impact will get upset with the delay? Is there away around it? (As far as I can see, my cable doesn't respond to the speed setting in Impact)
Any suggestions would be appreciated.
johannes