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Help me identify a RS232 port/connector

cjs said:
This is simply false. I use cheap AliExpress 24 AWG wire in my connections, and I test every single one I crimp with a force greatly exceeding the disconnect force, and I've never seen the insulation fail. Not once. (If they fail the test, it's invariably due to a bad crimp.)

Are you telling me that today's cheap wire from AliExpress is somehow of vastly higher quality than the high quality stuff "back in the days"?
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Even if you've anecdotally observed great outcomes, I've seen a lot of these fail. Using "more force" to crimp than is correct is more likely in my experience to damage the wire and connector, and can result in it cutting the wire in places and reducing overall clamping and contact area.

If you can't show a datasheet that recommends that the stress be taken by the cables and not the connector when disconnecting a plug, then you're probably using them incorrectly.

If you think about it, pulling a single plug by the wires is probably OK, but the moment you have two or more wires into the same termination, then invariably the stress of pulling two wires, especially if they are ribbon connected, will not tension all of the crimps equally and some crimps will transfer more force into the connector than others simply because it's not possible to get them all exactly the same length when pulling from any point on the cable. That's not a good thing. You'll probably get away with it, and I've done it in a pinch too, but I am very careful when I do it, and if the connector doesn't come loose straight away with minimal force, I stop and reconsider my approach.

The upper section of the crimp is for strain relief, but it's not intended to be a mechanical point for connection and disconnection. That's what the plug is for.

And locks/latches/catches on connectors are to address the possibility that the friction forces on the pin header may not be enough in some situations (eg, when the cables are subject to potential regular forces such as in mobile equipment)

I've pulled many cables in my lifetime, and many times I've ended up with a wire coming out of a crimp - even when the crimps were heavy duty made for arcade machines - not a set of pliers, but a large machine purpose built to crimp a lot of wires.

Perhaps you have personally solved this problem with your technique - I'll credit the possibility - but the rest of the world hasn't yet and when I see a crimped cable I have no idea of it's origin and how well it was crimped.
 
cjs said:
Are you telling me that today's cheap wire from AliExpress is somehow of vastly higher quality than the high quality stuff "back in the days"?
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Yes, some things were just awful back in the days. IIRC on this type of cable the inner insulation would shrink if you soldered the wire.

Another awful thing from back in the days were DIN plugs for soldering, that wouldn't withstand the heat from soldering. You had to mate them with a matching DIN socket to ensure that the plastic wouldn't deform resulting in the pins looking like Marty Feldmans eyes.

Another awful thing was that the outer shield of "phone connectors" (tip-sleeve/tip-ring-sleeve connectors) were either made of metal (great but expensive) or bakelite (or whatever you'd call hard plastic). The only exception was molded connectors. If you in the 70's had some off-brand headphones the plug wouldn't withstand being dropped onto the floor without the outer sleeve breaking. It was super common to see these outer shields broken and "repaired" using tape.
(I don't know what actually changed things, but I wound think that at the fall of the iron curtain either some east bloc manufacturer stopped producing the worlds supply of bakelite outer shields for these connectors (I've read somewhere that the Soviet KGB destroyed an electronics factory in Hungary when they thought that Hungary was opening up to the west too fast; not sure if that is true), or some east block factory started making plastic outer sleeves for these connectors, putting whoever made the bakelite ones out of business. I would think that whoever made the bakelite ones just continued as there was no other use for the manufacturing process. Compare with for example Quantum Bigfoot 5.25" hard disks that I think they produced at least partially due to there were existing manufacturing equipment for making 5.25" drives that would otherwise just be scrapped).

As for what is sold cheap on AliExpress: I would think that there isn't much to save when selling cables. If you today manufacture sub par cable, you can only sell it to various AliExpress sellers, which probably makes it hard to justify manufacturing that type of cable. This is in contrast to the fake automotive fuses and terrible butt connectors Louis Rossman did videos on, as the fuses can be made by just using a cheaper incorrect metal in the existing manufacturing process and the quantities would be as little as whatever the size of the metal sheets are. For the butt connectors, just cut the right length of the cheapest metal pipe ever and add an outer sleeve - again the plastic part can be the same as for "real" connectors.
 
MiaM said:
Yes, some things were just awful back in the days. IIRC on this type of cable the inner insulation would shrink if you soldered the wire.
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Well, let's keep in mind that that, in and of itself, is not a problem for cable intended to be crimped. Though I have difficulty believing that wire designed for soldering was that hard to get, given that back around 1980 apparently my junior high school managed to source 24 AWG stranded insulated wire that didn't have this problem. (I and my classmates melted plenty of the insulation on that, sure, but that was quite clearly our soldering technique, not the wire.) It would also seem odd that wire designed to work with this particular "dupont" style of crimping was not widely available from the 50s when this style of connector was invented as Berg's Mini-PV connector.

I would also be careful with evidence that DIN plug plastic was seriously worse: merely softening the plastic enough that the pins misaligned is still plenty frequent today (I've done it a lot myself), especially for those with not-great soldering technique who are also not using the correct (yet cheap and easily available) jig. 🥔

But again, it all comes back to remembering that each technique has its advantages, disadvantages and costs, and required techniques. Using "dupont"-style crimped connections surely doesn't provide the kind of strain relief you're looking for in your particular application, nor perhaps the number of connect/disconnect cycles you'd want for it. That doesn't mean that it's not good enough in, e.g., the application in the original post here.

But especially using things incorrectly, such as not realising where the strain is designed to be absorbed in those connectors, will lead to worse results. The classic example is actually putting a dab of solder on a crimped connection: there's almost no better way to make a good crimp weaker and more likely to fail than doing that, unintuitive as that might be to some.

People choose "inferior" methods of doing things all the time. Soldering is a huge example; since the "good old days" it's become so widespread that it has completely replaced significantly superior wire wrapping, yet nobody complains because it's cheaper, often easier, and good enough. (Replaced in most applications, I should say; back in the '60s the phone companies switched wholesale from soldered to punch-down connections for most of their wiring, for very good reasons, and have never looked back.)
 
cjs said:
I would also be careful with evidence that DIN plug plastic was seriously worse: merely softening the plastic enough that the pins misaligned is still plenty frequent today (I've done it a lot myself), especially for those with not-great soldering technique who are also not using the correct (yet cheap and easily available) jig. 🥔
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Oh, this is a whole other interesting and related topic you bring up about both the cables and the insulation especially and the plastic in the materials as well...

There's notable movement there with Phthalates now being banned and removed from PVC ( pretty much all cable insulation from the era, most modern stuff etc ) due to extreme toxicity - and it's going to leach out from all the old remaining cables too, reducing their strength and plasticity. The science of plasticizers is interesting - and I'm not an expert there - just curious from what I've read about it.

Nasty stuff. So plastics used in cables from the 80s and modern plastics are often significantly different.

And just how do you tell if the roll of PVC-insulation-laden-with-phthalates ribbon cable you're using is quality old stuff, bad old stuff, modern bad stuff, or who knows what? I would even wonder how many companies make ribbon cable nowadays. It's not like laws have caught up and modern plastics are labelled any differently. Cables don't come with date codes.

MiaM said:
Another awful thing from back in the days were DIN plugs for soldering, that wouldn't withstand the heat from soldering. You had to mate them with a matching DIN socket to ensure that the plastic wouldn't deform resulting in the pins looking like Marty Feldmans eyes.
Click to expand...


I've never figured out how to successfully solder DIN plugs myself. Sometimes I get good ones and they solder instantly but other times, I just can't get the solder to stick even with flux and a hot iron, and get get the same plastic shrinking as I'm trying to get the wire to stick to the pin... I usually use a socket to hold the din plug when I'm doing this - if there are jigs available I've never seen them so please link to one so I can order it...

And of course, related problems with the heat and flux and solder now travelling up the wire and soldering all the strands together and making it brittle well past the strain relief provided by the plug. So that wires literally break off inside the insulation with regular movement.

I still have to regularly solder DIN plugs and I hate it. Ordering newer ones seems to help a little though. Maybe there are good ones and bad ones and I'm just so used to the bad ones I think all of them are like that now?
 
Bruce Tomlin said:
those are just dupont style 0.1" connectors (or IDC connectors), and who knows that the pinout is unless you can find it on google image search, it might not be RS-232, just TTL serial

(I actually have one lying around, but never had time to mess with it beyond dumping the ROM and noticing it has a Z180)

This is really all I know about it:


and it's probably 9600-8-N-1
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Hi Bruce, did you ever make any progress on this? I was never able to get a pin-out. Obviously you can change the serial port settings in the status menu; you probably figured that one out. Unfortunately my soldering skills aren't really up to snuff to start to try to make cables.
 
Other than the mechanical connection, which seems to be the focus recently, you will need to know what pins do what. Since I don't think these connectors were standardized for RS-232, like DB-9 and DB-25 connectors, you may have to seek a schematic or even open the unit and trace the lines.
 
Or one can simple read the manual that Bruce posted a link to earlier in this thread:
Code: 
APPENDIX C: TECHNICAL DATA ABOUT PORTS

The following technical information provides special  cabling arrangements for
using the Braille 'n Speak with devices for which we do not offer specific
cables.

The Braille 'n Speak is a DCE device.  You'll need a null  modem cable to
interface the unit with other DCE  devices.

The Braille 'n Speak has two female interface ports. Either can be used for
the disk drive (Chapter 14), a computer, modem, or any other serial  device
(Chapter 15.  Below, we list their active pin assignments  for your
convenience.  (Note that the cable we provide for this port has eight pin
locations on the end which connects to  the port and 25 pin locations at the
end that connects to an  external device.)

Pin 1 - DTR
Pin 2 - CTS
Pin 3 - TX
Pin 4 - GND
Pin 5 - RX
Pin 6 - DTX (for disk drive)
Pin 7 - DRX
Pin 8 - DON
 
tingo said:
Or one can simple read the manual that Bruce posted a link to earlier in this thread:
Code: 
APPENDIX C: TECHNICAL DATA ABOUT PORTS

The following technical information provides special  cabling arrangements for
using the Braille 'n Speak with devices for which we do not offer specific
cables.

The Braille 'n Speak is a DCE device.  You'll need a null  modem cable to
interface the unit with other DCE  devices.

The Braille 'n Speak has two female interface ports. Either can be used for
the disk drive (Chapter 14), a computer, modem, or any other serial  device
(Chapter 15.  Below, we list their active pin assignments  for your
convenience.  (Note that the cable we provide for this port has eight pin
locations on the end which connects to  the port and 25 pin locations at the
end that connects to an  external device.)

Pin 1 - DTR
Pin 2 - CTS
Pin 3 - TX
Pin 4 - GND
Pin 5 - RX
Pin 6 - DTX (for disk drive)
Pin 7 - DRX
Pin 8 - DON
Click to expand...


Thanks but that manual pertains to the later Braille and Speak 2000, also known as the BS2; which has round (DIN) female ports. The unit we are speaking about is the earlier BS1 with square Dupont style male ports.
 
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