focus cable

[dmahon]

Is the cable from a focus controller to a stepper motor (robofocus, lakeside, sharpsky, etc.) just a standard straight through serial cable?

[ronin]

You would have to trace it through to find out.

Some will take the easy route and have it straight through, they can then just buy in standard items. Others will cross some over or reverse the whole lot on the basis that you then have to go back and buy from them. More sales.

[dmahon]

I found out its a straight through cable - which you can buy as a VGA extension cable off the shelf.

[perfrej]

Straight. You can extend it with a 9-pin serial cable. Only 1-5 is used.

/p

[dmahon]

I thought a standard serial cable has a few crossed wires?

[perfrej]

Standard serial cables are straight and have a female in one end and a male in he other. The diagram posted does not work. When the left interface generates a request to send, the right one gets a clear to send. Doesn't work that way, even though many sites on the internet pose that connection scenario. If a null modem is desired, as per the diagram, the left part's 7 and 8 should be wired together and not connect to the counterpart. Same on the right.

/per

[dmahon]

Thanks - it's so long since I had used serial cables I had forgotten how they were wired (not since I ran a bulletin board in the 80s). Such old technology. Anyway, yes, of course you're right - a standard serial cable is straight through.

Despite the label on that picture on the original website, it's a true null modem cable (with RTS/CTS crossed, rather than a really "dummied" cable like you mention where they are fed back to themselves).

(and a VGA monitor cable is 15 pin, I just took what I was told at face value - maybe he meant an EGA cable when he said monitor cable).