Problem with MFFS rennet cables

Hello I'm trying to make a computer return true if a MFFS rennet cable is white and powered. Ive done multiple google searchs and couldn't find any help, how exactly would I do this?
Code:

while true do
print (colors.test (redstone.getBundledInput("back"), colors.white))
sleep(1)
end

Screenshots: http://imgur.com/a/G7nGe

Your code's "correct", but could be simplified at least a little:

while true do
  print (rs.testBundledInput("back" , colors.white))
  sleep(1)
end

If you stick a bit of redstone dust on the end of the cable (as opposed to a computer), does that light up to show the signal is being carried?

Depending on the exact builds of CC / MFR you're using, you may need to update one or the other or both.

Bomb Bloke, on 11 July 2016 - 12:54 AM said:

Your code's "correct", but could be simplified at least a little:

while true do
  print (rs.testBundledInput("back" , colors.white))
  sleep(1)
end

If you stick a bit of redstone dust on the end of the cable (as opposed to a computer), does that light up to show the signal is being carried?

Depending on the exact builds of CC / MFR you're using, you may need to update one or the other or both.

I have the latest version of ComputerCraft and MFFS for 1.7.10, the computer still prints out false. Screenshots: http://imgur.com/a/h5GKv

He meant update MFR (MineFactory Reloaded), not MFFS (Modular Force Field Systems), try updating MFR instead.