@Ken, That is correct. And the reason behind why long wire and digital tests doesnt mix is that the long wires present a capacitive structure that allows the digital signals to couple over to the adjacent wires. This is crosstalks. In some cases, if the logic level of the digital signal is high, like CMOS or TTL level, a little crosstalk is tolerable. However, when the logic level goes lower, it is probably impossible to get a stable test over the long cables.
Some tester uses special cables(eg, coaxial cable) to handle their digital tests, like SPI, I2C programming. But then, this make it dedicated to the specific test points on the fixture... not a very flexible method.
Edited by: adrianc on Mar 20, 2012 10:08 AM
Now this is where the i1000D makes a difference in the digital test. The i1000D digital pin card support both analog and digital resources. each digital resource on the card is matched with its own ground to that crosstalk can be minimised along the long cabling. This method allows the i1000D to perform different digital tests like Serial programming (SPI, I2C), Boundary scan, etc.