Probably --not certainly but probably-- one input and one output, So the one with appreciable voltage between it and ground (6 to 12 volts) would be the output that the controller uses to acknowledge input (TD). The other one, with a few millivolts between it and ground would be the input (RD).
Possibly one of these pinouts
A 9-pin is the same for 2 and 3 but the ground is on 5 according to info I found here:
"I'm not grown up enough to be so old!"
They are almost certainly Transmit, Receive, and Common (or ground).
This may help:
The voltages are bipolar ~12VDC, so you can usually figure them out with a meter.
There are two type of connectors used in RS-232, DB-9 (9 pins) and DB-25 (25 pins).
The PC end of the cable will be a female, I have no idea what is on your CNC machine.
RS-232 is very tolerant of miswiring, so you might just try a straight through cable and if that doesn't work, try a null-modem (otherwise known as a crossover) cable.
HTH
Mike Patterson Please remove the spamtrap to email me.
I seem to recall that the machine side of this link used a non-standard round connector with a bayonet locking ring instead of a DB9/DB25 so it's not as easy as simply trying standard cables...
Machine: Vintage Boss 6 BP CNC. Accepts commands from a PC via RS-232, rather than a tape generated program.
The CNC CAD/CAM program looks great, the post processor working perfectly, but...........and here's the question, we need to find the pin-outs for the serial cable; three wires plus ground from the controller. Any input? All is appreciated.
|Machine: Vintage Boss 6 BP CNC. Accepts commands from a PC via RS-232, |rather than a tape generated program. | |The CNC CAD/CAM program looks great, the post processor working perfectly, |but...........and here's the question, we need to find the pin-outs for the |serial cable; three wires plus ground from the controller. Any input? All is |appreciated.
Sounds like the simplest of basic RS-232 cables. I've pulled my hair out over serial cables just as simple, until I ran across the sure-fire solution that works everytime, connecting any two serial devices: SmartCable They use a small logic chip. Just connect it, with adapters if neccessary, and try some output with the slide switch in one of the 3 postitions. One will always work. Rex in Fort Worth
Its serial communication Func DB-9 PIN# DB25 pin# Rec Data 2 3 Trans data 3 2 Clear send 8 5 Request send 7 4 Data set ready 6 6 Signal ground 5 7 Data term ready 4 20 Data carrier 1 8
now sometimes I had "short not really" on a db9 pins pins 7 and 8 or others. this was to tell the PC to send the data even if the machine wasn't "ready" You have to play with baud rates to get it to go smooth. I will see if I can find my notes on what pins I had to wire to each other.
Others have reported on the pin names but you need to remember that there are several more pins on the computer end that may need to be tied together in order to get the computer to output a signal. Voltages are typically about +/-9V or so. Anything more than 5V is good for a signal level although the computer will put out something between 9 and
12V ususally. At the machine end with only 3 pins, one will indeed be tied to an electronic ground, one will have a definite voltage on it and the third will usually just be seemingly open. If you don't have an original cable (even with a broken wire inside) you can fight the problem for a long time if you don't know what is happening with that system.-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!
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Not just a non-standard round connector (connector made by AMP, BTW), but it also mixes both RS-232 and 20mA current loop in the same connector. I believe that the ground pin is shared between the two interfaces. And I believe that a jumper is needed in the receive side of the current-loop when RS-232 is in use -- but it might be DIP switches on the interface card instead.
I should be able to look it up, if nobody else finds the information first.
Good Luck, DoN.
Not much use in this case, since the connector is neither the DB-9 or the DB-25, but rather a round moulded connector by AMP, in which both minimal RS-232 (TXD, RXD and signal ground) are mixed with
20mA current loop (dates back to the old ASR-33 Teletype days.)Good Luck, DoN.
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