Hi Mart,

My apologies for the really late reply.  Basically, the reason why j frolich needed to create a modified version of the firmata is because that particular ping sensor doesn't output a standard analog output.  The firmata is setup to read (digital and analog) values from the appropriate pins.  However, to get the ping sensor to work properly, you need to send a brief digital pulse out to the sensor on a pin to trigger the detection and then wait for a return pulse after the sound has echoed off of an object.  Here's a good explanation (http://www.arduino.cc/en/Tutorial/Ping).  So to get an actual reading from these sensors, you're sending a receiving signals very quickly on a standard digital pin.  The firmata simply tells the microcontroller to do a digital read... but you need to do a digital write and a digital read (all of this is happening very quickly).  So, there's a little bit of difference in how this particular sensor is configured in order to get a reliable value (compared to other sensors).

So, the easiest solution for all of this if you aren't comfortable with coding would be to simply use two arduino boards (if you have an extra one available).  On one of them, you could load up j frolich's modified firmata to get your ping sensor values.  On the other you could load up the standard firmata to control your servos etc.  The key would be to know that you will also need to use two Open/Close port components since you're going to be communicating with two separate arduino boards.  In addition, when you specify the port input on the read and write components, you'll need to know which board is connected to the sensor and which one is connected to the servo (so you send the right command to the right board).  Hopefully this makes sense.  Let me know if you have any additional questions.