can we measure TTL output using a multimeter?

Hi all, i am working on a pen wand scanner (MSH-119) project. The output of the scanner is TTL data. My question is: can we measure the TTL output using a multimeter? I tried it but the output is always 5v (I connect a pullup resistor 5.1k between the power and the TTL output) no matter where I place the tip of the pen on. The datasheet says Black = high logic level, white = low logic level.

I also tried to feed the TTL output to pin0 (RX) of my arduino UNO, but i am getting nothing. Here is my code

int incomingByte = 0;   // for incoming serial data

void setup() {
        Serial.begin(9600);     // opens serial port, sets data rate to 9600 bps
        pinMode(0, INPUT);
}

void loop() {

        // send data only when you receive data:
        if (Serial.available() > 0) {
                Serial.print((char)Serial.read());
        }
}

Not that fast a signal. A high or low or a few couple pulses a second maybe.

Or try this Poor Man's logic probe: http://forum.arduino.cc/index.php?topic=245712.0

You can make a crude pulse tester probe with a couple of LEDs and a couple of resistors. Wire one LED/resistor between the probe-input and ground so that it comes-on when the probe is connected to 5V. Wire the other LED/resistor between the probe-input and 5V so it comes-on when the probe is low/grounded.

With "normal data" switching between high and low, both LEDs should glow and/or flicker somewhat dimly. And, you can read constant-high or constant-low. The only problem is when you have short pulses or infrequent pulses, you may not see anything happening.

You can also buy (or build) a slightly more advanced [u]logic probe[/u] that can detect short pulses.

But, it's hard to beat an oscilloscope! ;) (I don't own a 'scope, but I have a couple at work.)

Use a cheap 8 channel logic analyzer. I have one of these and it works quite well. $9.97 and free shipping. http://www.ebay.com/itm/Logic-Analyzer-USB-Logic-24M-8CH-8Channel-24MHz-Latest-Supports-1-1-15-Free-Ship-/181457072196?pt=LH_DefaultDomain_0&hash=item2a3faf3044

Scope or logic analyzer gets my vote.

In the absence of a proper scope of analyser, I’d expand on the sketch, but forget about using the chip’s UART.
Look for a steady state on an input and start capturing when you see an edge.
Just put a bunch of edge timestamps into a buffer and print the results when the line returns to a steady state or when the buffer is full.

AWOL: Look for a steady state on an input and start capturing when you see an edge. Just put a bunch of edge timestamps into a buffer and print the results when the line returns to a steady state or when the buffer is full.

Something like this but more polished.