Title
----- 
Point Control v1


Goal
----
What is a track layout without points (switches)? If you plan to control a 
complete laypout, then you also must control points.


Solution
--------
First of all the points must be motorized. Several solutions are available
on the internet. I prefer the solution by Mark Riley because it's compact
and doesn't need to modify any LEGO part. See also his website:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=44666
http://home.surewest.net/markril/lego/index.html 

Hook up three points to the RCX, download the program and you're ready to
control your points. Please keep the following things in mind:
- Switching two or more points immediately after each other require a 
  delay of 500 ms between two switches otherwise messages will be lost
  by the receiver/controller. This value is based upon some tests. Therefore
  I propose a solution like in the test program.
- When the program starts, all three points are set to the straight position.
  It's important that you connect the electric wire brick correctly on the 
  RCX: for a right point put the wire as you normally would; for a left
  point turn the wire 180 degrees. 


Bill Of Materials
-----------------
1x RCX (receiver/controller)
1x RCX (sender; also possible is to use Bricx Command Center for sending)
3x Point
3x Motor + additional bricks to build the motorized point
3x Electric Wire


Limitations
-----------
This concept only works for 3 points per RCX brick. Large layouts often
have a lot of points especially when you include a yard in your layout. I 
need to figure out a way how to control many points with just 1 RCX. 
Another remark is that the input ports are not used. Ofcourse you can add 
light sensors for detecting a train, but then you probably should send a
message to another RCX which handles the event? In the end that will 
result in spaghetti design.





Stefan Sanders
StefanSanders@Wanadoo.nl