Energy cell power monitor v2

-- Monitors TE3 Energy cells and EnderIO capacitor banks and output redstone signals once energy storage drops below set limits.
-- Will automatically detect direction of adjacent storage device and (optional) Advanced Monitors. If chosen, monitor format should be 1 high and 2 wide.
-- Redstone signal for the engines will be output out the back of the computer.
--More details: http://forum.feed-the-beast.com/threads/rhns-1-6-monster-build-journal-and-guide-collection.42664/page-15#post-718973


local upper = 0.90 --Upper limit for computer to stop transmitting redstone signal. 0.90=90% full.
local lower = 0.10 --Lower limit for computer to start transmitting redstone signal.


--Device detection
isError=0

function detectDevice(DeviceName)
DeviceSide="none"
for k,v in pairs(redstone.getSides()) do
 if peripheral.getType(v)==DeviceName then
   DeviceSide = v
   break
 end
end
  return(DeviceSide)
end

MonitorSide=detectDevice("monitor")

if MonitorSide~="none" then
      monitor=peripheral.wrap(MonitorSide)
   print ("Monitor on the " .. MonitorSide .. " connected.")
   else
   print ("Warning - No Monitor attached, continuing without.")

end

CellSide=detectDevice("cofh_thermalexpansion_energycell")

if CellSide~="none" then
      cell=peripheral.wrap(CellSide)
   print ("TE Energy cell on the " .. CellSide .. " connected.")
   else
    CellSide=detectDevice("tile_enderio_blockcapacitorbank_name")
    if CellSide~="none" then
        cell=peripheral.wrap(CellSide)
        print ("EnderIO capacitorbank on the " .. CellSide .. " connected.")
    else
        print ("*ERROR* - No Energy storage attached, halting code!")
        return
    end
end


--Main code
redstone.setOutput("back", false) --Defaulting to off

--If monitor is attached, write data on monitor
if MonitorSide~="none" then
    monitor.clear()
    monitor.setBackgroundColour((colours.grey))
    monitor.setCursorPos(1,4)
    monitor.write(" ON ")
    monitor.setBackgroundColour((colours.green))
    monitor.setCursorPos(5,4)
    monitor.write(" OFF ")
    monitor.setBackgroundColour((colours.black))
end

--Main loop
while true do
    --Get storage values
    eNow = cell.getEnergyStored("left")
    eMax = cell.getMaxEnergyStored("left")

    --Compute ratio
    fill = (eNow / eMax)

--If monitor is attached, write data on monitor
if MonitorSide~="none" then
    monitor.setCursorPos(11,2)
    monitor.write("Storage:")
    monitor.setCursorPos(11,3)
    monitor.write(eNow)
    monitor.setCursorPos(11,4)
    monitor.write("Of:")
    monitor.setCursorPos(11,5)
    monitor.write(eMax)

    monitor.setCursorPos(1,2)
    monitor.write("Engines:")
end

    if fill > upper then
        --energylevel is over upper level, turning redstone signal off
        redstone.setOutput("back", false)

        if MonitorSide~="none" then
            monitor.setBackgroundColour((colours.grey))
            monitor.setCursorPos(1,4)
            monitor.write(" ON ")
            monitor.setBackgroundColour((colours.green))
            monitor.setCursorPos(5,4)
            monitor.write(" OFF ")
            monitor.setBackgroundColour((colours.black))
        end

    elseif fill < lower then
        --energy level is below lower limit, turning redstone signal on
        redstone.setOutput("back", true)

        if MonitorSide~="none" then
            monitor.setBackgroundColour((colours.green))
            monitor.setCursorPos(1,4)
            monitor.write(" ON ")
            monitor.setBackgroundColour((colours.grey))
            monitor.setCursorPos(5,4)
            monitor.write(" OFF ")
            monitor.setBackgroundColour((colours.black))
        end
    end


    sleep(1)
end --while