[.Netframework] script that control object via serial port

hello, i am working on project that transferring data from micro-controller
using serial port to effect object in 3Ds max

ex.

0.75,0.60,5.03
0.62,1.34,9.36
0.50,2.06,13.07
0.38,2.75,15.60
0.26,3.41,17.73
0.16,4.06,19.51

and i have researched alot to find some maxscript similer to my project and i found this :-

	port = dotNetObject "System.IO.Ports.SerialPort" "COM3" 115200
	port.parity = port.parity.none
	port.databits = 8
	port.stopbits = port.stopbits.one
	port.handshake= port.handshake.RequestToSend

	 rollout MinImu "MinImuToMax"  width:90 height:150
	 (
	dotNetControl dn_labelPR "System.Windows.Forms.Label" text:"seconds" pos:[20,10] width:50 height:20
	dotNetControl textboxctrl "System.Windows.Forms.TextBox" pos:[20,30] width:50 height:30
	button Frames "Frames" width:50 height:20 
	button Start "Start" width:50 height:20
	button Stop "Stop" width:50 height:20
		 
	on Frames pressed do 
	 ( 
	 	finSec = textboxctrl.text as integer
		finFrame = finSec * 25
		 animationRange = interval 0 finFrame 
		
	 )
	 
	 on Start pressed do --the button
	 ( 

	port.Open()
		 
	 	finSec2 = textboxctrl.text as integer
		finFrame2 = finSec2 * 25	 

	for i= 1 to finFrame2 do

	 (
		      	 
	 rotValue = port.ReadLine() as string
		 --encontramos las letras
		 r = findstring rotValue "r"
		 p = findstring rotValue "p"
		 y = findstring rotValue "y"
		 en = findstring rotValue "e"
		 --las convertimos en numeros float
		 r2 = r as float
		 p2 = p as float
		 y2 = y as float
		 en2 = en as float
		 --asignamos limites del substring	 
		 r3 = r2 + 1
		 p3 = p2 - 2
		 p4 = p2 + 1
		 y3 = y2 - p4 
		 y4 = y2 + 1
		 en3 = en2 - y4
		 --aislamos roll pitch yaw
		 roll = substring rotValue r3 p3
		 pitch = substring rotValue p4 y3
		 yaw = substring rotValue y4 en3
	     --convertimos roll pitch yaw en numeros float
		 rollValue = roll as float
		 pitchValue = pitch as float
		 yawValue = yaw as float
		 --imprimimos roll pitch yaw 
		--print rollValue
		--print pitchValue
		--print yawValue
		 --enviamos valores a la caja
		 if rollValue != undefined then
	 (
	 	$caja.rotation.controller.x_rotation = rollValue	
	 )
	 	 if pitchValue != undefined then
	 (
	 	$caja.rotation.controller.y_rotation = pitchValue *-1	
	 )
	 	 if yawValue != undefined then
	 (
	 	$caja.rotation.controller.z_rotation = yawValue *-1	
	 )

	 completeRedraw()
	 sliderTime += 1

	 )
	 )
	 
	 on Stop pressed do
	 (
		 port.Close()
	 
	 )
	 
	 )
	 
	createdialog MinImu
	 
)

what i understood from that code, is that maxscript opens the port to receive data (COM3 for ex.) and then it searches for the line with r and read the coordinates to affect the object named caja

but the problem is that i always facing this message

" -- Unable to convert: undefined to type: Float "

i hope to find help here, i am a beginner at MaxScript

Regards,
Hisham ..