DC-16 to the max many questions

[neon_kenny]

I've used multiple DC-16's successfully where I've driven as many as 192 channels via 3 Prop-1 pins and 4 DC-16's on each. I have a project where I need to push further and realized I don't know the answers to a few things:

1. Can multiple DC-16's set to the same address be on the same serial line? If so what would be the practical limit i.e. does the serial power drain off after x number of boards? Or is there a time penalty as each board receives signals? Would they drift out of synch?

2. What is the practical length that the serial connection can run? Is there a chance of crosstalk if many serial lines are in proximity? Should the wire gauge increase? Would a shield help?

3. Possibly answered somewhere but has anyone found a simple chip or board that easily increases the output current of the ULN2803 or ULN2003?

Thanks in advance!

[JonnyMac]

1. Yes, but we've only ever tested with four boards under short-run conditions -- as we would expect in a prop.  If you connect multiple boards to the same serial pin and they have the same address they will do the same thing.

2. Remember this is TTL serial and there is not a lot of drive current from the chip; I wouldn't go beyond 10 feet or so -- but only testing will tell.  Yes, larger wire that is twisted and shielded will help.  Using a slower baud rate helps fight the capacitance of the long cable.

3. The ULN2x03 output is what it is.  I've seen a similar chip that includes a shift register that supports a bit more output, but it is not pin-compatible with the ULN.  You may need to go with a custom circuit.

[neon_kenny]

Thanks!