Just confirming SER1 to PC COM adapter

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Chr$
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Just confirming SER1 to PC COM adapter

Postby Chr$ » Mon Jan 20, 2020 7:09 pm

Ok, just to properly verify the correct method of making an adapter cable for a PC COM port to German QL Spec SER1, because there is conflicting info out there, I don't know much about these things, need to get my head round it and I want to be sure

(basically, it's so that I can print to a QL printer from my PC COM port which has a QXLII installed. The printer has a 9 pin D female connector and works perfectly with my German spec BBQL in SER1).

The pins of the connector are numbered like this:

Male pin connector from the front of it, i.e. the business end and not the solder or hidden side - Pin 1 is top row leftmost and pin 5 is top row on the right. Pin 6 is bottom row leftmost and pin 9 is bottom row on the right.

Pins are as follows:

PC Socket.....German QL
1. DCD...…...1. Ground
2. RXD...…….2. TXD
3. TXD...…….3. RXD
4. DTR...…….4. DTR
5. GND...…….5. CTS
6. DSR ………..6. 0 volt
7. RTS...…….7. 0 volt
8. CTS...…….8. 0 volt
9. RI...……...9. +12v

So if that is correct there are a few things I'm not sure about... to make the correct adapter I will need to cross over the following:

Pin 1?
Pin 2 to pin 3 (RXD)
Pin 3 to pin 2 (TXD)
(4 stays to 4)
Pin 5 to 7 (Gnd)
Pin 6?
Pin 7?
Pin 8 to 5 (CTS)
Pin 9?

I suspect those I've marked with a ? are mostly unused? But what about the +12v on the PC pins, where is that? And the RTS on the PC, does that need to go somewhere!?

Thanks.


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 2x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

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janbredenbeek
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Re: Just confirming SER1 to PC COM adapter

Postby janbredenbeek » Mon Jan 20, 2020 11:25 pm

Chr$ wrote:Ok, just to properly verify the correct method of making an adapter cable for a PC COM port to German QL Spec SER1, because there is conflicting info out there, I don't know much about these things, need to get my head round it and I want to be sure

(basically, it's so that I can print to a QL printer from my PC COM port which has a QXLII installed. The printer has a 9 pin D female connector and works perfectly with my German spec BBQL in SER1).

The pins of the connector are numbered like this:

Male pin connector from the front of it, i.e. the business end and not the solder or hidden side - Pin 1 is top row leftmost and pin 5 is top row on the right. Pin 6 is bottom row leftmost and pin 9 is bottom row on the right.

Pins are as follows:

PC Socket.....German QL
1. DCD...…...1. Ground
2. RXD...…….2. TXD
3. TXD...…….3. RXD
4. DTR...…….4. DTR
5. GND...…….5. CTS
6. DSR ………..6. 0 volt
7. RTS...…….7. 0 volt
8. CTS...…….8. 0 volt
9. RI...……...9. +12v

I'm not aware of the pin layout on German QLs, but I believe the direction of TXD/RXD and DTR/RTS lines on SER2 will be reversed with respect to SER1 as with UK models. In any case you should use SER2 as SER1 is already occupied with the printer.
You should connect both DCD and DSR on the PC side to +12V as this indicates to the PC that the 'QL null modem' is present and there is a 'carrier'. RTS on the PC should be connected to CTS on the QL and CTS on the PC to DTR on the QL for proper flow control. GND should be connected to GND.

There's a lot of info on the QL's serial ports on Dilwyn's site: http://www.dilwyn.me.uk/gen/serial/serial.html

Jan


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Chr$
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Re: Just confirming SER1 to PC COM adapter

Postby Chr$ » Mon Jan 20, 2020 11:44 pm

janbredenbeek wrote:I'm not aware of the pin layout on German QLs, but I believe the direction of TXD/RXD and DTR/RTS lines on SER2 will be reversed with respect to SER1 as with UK models. In any case you should use SER2 as SER1 is already occupied with the printer.
You should connect both DCD and DSR on the PC side to +12V as this indicates to the PC that the 'QL null modem' is present and there is a 'carrier'. RTS on the PC should be connected to CTS on the QL and CTS on the PC to DTR on the QL for proper flow control. GND should be connected to GND.

There's a lot of info on the QL's serial ports on Dilwyn's site: http://www.dilwyn.me.uk/gen/serial/serial.html

Jan

That confuses me more. Dilwyn's site has the pins around the other way, i.e. from the back on the port, pin 1 is top left etc.

Then I don't fully understand this chart:

pinsql.jpg


which has e.g. pin 7 as 12v and 1 as n.c.... which is completely different to the info that Urs copied from the German QL manual (1=gnd and 7 is 0v).

I suppose I should rig something up with connectors that I can swap around easily and should also check for the 12v so I don't put that one where it shouldn't go!


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 2x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

Ask me about near NOS re-felted good quality Microdrive Carts - many available.
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bwinkel67
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Re: Just confirming SER1 to PC COM adapter

Postby bwinkel67 » Tue Jan 21, 2020 12:46 am

I agree, that table makes no sense. Since I have a US QL I just measured and pin 9 on the DB9 RST232 is giving out a 12 volt signal (grounded to pin 1). So it seems this one by Urs is more reliable:

QL-DB9.png


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dilwyn
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Re: Just confirming SER1 to PC COM adapter

Postby dilwyn » Tue Jan 21, 2020 9:13 am

Would it be possible for someone with more knowledge of the serial ports than I to have a look at the page and check if anything needs to be corrected or even removed? From what I can tell, the D-connector wiring looks more PC-style.

Maybe I should add Urs's diagram to that serial ports page (it's currently on a separate Hardware Docs page at http://www.dilwyn.me.uk/docs/hardware/index.html near bottom of page. Perhaps I could just cross-link from the serials page to this document on that page? Reluctant to make the change without help from someone who knows more about the subject than I do.

It's quite an old page - I remember the "no, it's not that way, it's this way" arguments when I first did that page, nobody seemed able to agree.


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All things QL: see www.dilwyn.me.uk
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dex
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Re: Just confirming SER1 to PC COM adapter

Postby dex » Tue Jan 21, 2020 11:15 am

According to my clever paper, I have connected my cable "QL SER2 to modem" (but now we need "PC to QL printer") this way:
1 GND to pin 5
3 TxD to pin 3
2 RxD to pin 2
4 RTS (DTR on SER2) to pin 7
5 CTS to pin 8
7 0V to pin 5
9 +12V - NC
(6, 8 NC)


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Chr$
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Re: Just confirming SER1 to PC COM adapter

Postby Chr$ » Tue Jan 21, 2020 12:28 pm

dex wrote:According to my clever paper, I have connected my cable "QL SER2 to modem" (but now we need "PC to QL printer") this way:
1 GND to pin 5
3 TxD to pin 3
2 RxD to pin 2
4 RTS (DTR on SER2) to pin 7
5 CTS to pin 8
7 0V to pin 5
9 +12V - NC
(6, 8 NC)


I think that's probably pretty similar to what I want. I don't think the printer is going to need the +12v either (as it has plenty of its own power).


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 2x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

Ask me about near NOS re-felted good quality Microdrive Carts - many available.
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janbredenbeek
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Re: Just confirming SER1 to PC COM adapter

Postby janbredenbeek » Tue Jan 21, 2020 3:35 pm

bwinkel67 wrote:I agree, that table makes no sense. Since I have a US QL I just measured and pin 9 on the DB9 RST232 is giving out a 12 volt signal (grounded to pin 1). So it seems this one by Urs is more reliable:

This is interesting. If this diagram is correct, this would mean German QLs have SER1 and SER2 reversed compared to UK models. See http://www.dilwyn.me.uk/docs/ebooks/olq ... .htm#comms for the UK model.
On UK models, SER1 is configured as DCE (i.e. a modem) and SER2 as DTE (computer). From a DTE's point of view, TxD is output and RxD is input. But the German wiring suggests that SER1 is configured as DTE (Senden = Transmit, Empfangen = Receive). You can test this by measuring the voltage on an idle port; if TxD is output then you should measure -12V on both TxD and DTR while the inputs should be close to 0V.
The +12V line is not meant as power supply (though some peripherals such as the Miracle Systems modem used it as such!), but to tell connected peripherals that the connection has been established (most notably DSR and DCD should be tied high on the PC end as some software expects this).

Jan


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Chr$
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Re: Just confirming SER1 to PC COM adapter

Postby Chr$ » Tue Jan 28, 2020 10:21 pm

Hello Jan,

I had a look inside the plug of the QL printer and only pins 1 - 5 and pin 9 are connected. I checked the voltages on those pins and got the following:

1 - 0v (def ground)
2 - nothing much detected
3 - minus 11v
4 - nothing much detected
5 - minus 11v
9 - plus 12v

So does that mean that from a PC COM port I would need to connect (I also checked the idle voltages on the PC port):

PC pin 2 (RXD, 0v idle) to QL printer pin 2 (TXD, 0v idle)
PC pin 3 (TXD, -12v idle) to QL printer pin 3 (RXD, -12v idle)
PC pin 4 (DTR, -12v idle) to QL printer pin 5 (CTS, -12v idle)
PC pin 5 (GND) to QL printer pin 1 (GND)
PC pin 8 (CTS, 0v idle) to QL printer pin 4 (DTR, 0v idle)
(and take +12v from a neighbouring COM port that has a +12v to the QL printer pin 9)

Does that make any sense at all??


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 2x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

Ask me about near NOS re-felted good quality Microdrive Carts - many available.
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janbredenbeek
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Re: Just confirming SER1 to PC COM adapter

Postby janbredenbeek » Wed Jan 29, 2020 12:03 am

Chr$ wrote:Hello Jan,

I had a look inside the plug of the QL printer and only pins 1 - 5 and pin 9 are connected. I checked the voltages on those pins and got the following:

1 - 0v (def ground)
2 - nothing much detected
3 - minus 11v
4 - nothing much detected
5 - minus 11v
9 - plus 12v

So does that mean that from a PC COM port I would need to connect (I also checked the idle voltages on the PC port):

PC pin 2 (RXD, 0v idle) to QL printer pin 2 (TXD, 0v idle)
PC pin 3 (TXD, -12v idle) to QL printer pin 3 (RXD, -12v idle)
PC pin 4 (DTR, -12v idle) to QL printer pin 5 (CTS, -12v idle)
PC pin 5 (GND) to QL printer pin 1 (GND)
PC pin 8 (CTS, 0v idle) to QL printer pin 4 (DTR, 0v idle)
(and take +12v from a neighbouring COM port that has a +12v to the QL printer pin 9)

Does that make any sense at all??

You're now connecting inputs to inputs and outputs to outputs, which doesn't make sense ;)
Pins 2 and 3 should be interchanged (RXD/TXD), and pin 7 on the PC (RTS) should be connected to pin 4 (DTR) on the printer (because this is the 'ready out' signal from the PC, though DTR on pin 4 will probably also work because you don't need flow control from printer to PC). The difference between RTS and DTR on the PC is that RTS is the real flow control signal and DTR stays at +12V as long as the PC port is active.
PC Pin 8 should be connected to printer pin 5 (CTS, which is 'ready out' for printer and 'ready in' for the PC). This is essential for flow control when sending data to the printer.
You might also want to connect pin 9 from the printer to pin 6 on the PC, as this pulls the DSR input on the PC high to indicate that the printer is online (on some PCs you should also connect this to pin 1 (DCD) too).

Jan



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