[SOLVED] Plotter cable DB9 to DB25 pinout?

Thread Starter

mhel

Joined Apr 17, 2008
4
Hi,
Long time lurker first time poster (I think).
I'm wondering if anyone could help me figure out the pin-out
for a DB9 to DB25 serial cable.
A friend has this old plotter, from late 90's that has DB25 serial
input. I'm trying to hook it up to a DB9, actually USB -> DB9 ->DB25.
(the USB to serial outputs +-10v). I found a user manual
and a service manual. I got the Tx and Rx pins figured out, but I can't
figure out the pins for the flow control.
 

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JohnInTX

Joined Jun 26, 2012
4,573
We;come to AAC!

https://en.wikipedia.org/wiki/RS-232
Has the pinouts of the different connectors. You can also buy 9 pin - 25 pin adapters with various gender combinations.
https://www.amazon.com/s?k=db-9+to+db25+adapters&ref=nb_sb_noss

Googling
rs-232db9 to db25 pinout
Gets lots of diagrams like this:
https://www.bb-elec.com/Learning-Ce...rence-Card-RS-232-DB9-DB25-pinouts-level.aspx

https://www.bb-elec.com/Learning-Center/All-White-Papers/Serial/What-Is-RS-232.aspx

Do use a quality USB-RS-232 adapter. The cheapies often do not work with the handshaking etc.

Good luck!
 
Last edited:

KeithWalker

Joined Jul 10, 2017
1,947
Are you sure the plotter interface is serial? A DB25 connector suggests to me that it is for the 2000 era parallel printer port. What is the make and model of the plotter?
 

JohnInTX

Joined Jun 26, 2012
4,573
Are you sure the plotter interface is serial? A DB25 connector suggests to me that it is for the 2000 era parallel printer port. What is the make and model of the plotter?
Most of the ones I used had Centronics connectors on the plotter but..

For TS, what is the make/model of the plotter?
 

Thread Starter

mhel

Joined Apr 17, 2008
4
Thanks for the replies guys.

The plotter is a Roland CJ-70, it's a print and cut, but the print is hopeless even if it would work parts is most likely non existent anymore. The cutting is showing signs of life. The USB to serial cable is similar to this https://www.adafruit.com/product/18

I've gone through a bunch of pin configuration but I can't get the flow control working.
The plotter complains about buffer overflow and says check the handshake. The program is set
to use hardware flow control with DTS, DTR, CTS, RTS enabled.

BTW, the plotter has Centronics for the LPT, and DB25 for the RS232.
 

SamR

Joined Mar 19, 2019
3,537
Before you even get too far into it, can you find a printer driver and application that will even access the plotter with your current operating system? A lot of technology has been developed in the last 30 years and old hardware usually ends up in the landfill.
 

Thread Starter

mhel

Joined Apr 17, 2008
4
Thanks guys, I think I've sorted it out following this: https://ltrxdev.atlassian.net/wiki/spaces/LTRXTS/pages/105906724/RS232+Serial+Cable+Wiring PC to DTE DB25.
It still feels like it's not correct, the plotter seems to pause between moves like it's waiting for data.
Or it could just be too old for a machine.

The confusing part is/was the user manual has pin 5 named, but the schematic on the service manual does not have a connection.

It's a real waste to put it to scrap, the linear rail at >= 50" length is quite expensive. If it didn't work
I could probably retrofit it with grbl :)

Thanks again guys.


edit:
How does one mark the thread as solved?
 

JohnInTX

Joined Jun 26, 2012
4,573
Glad you got it working. I was sketching out more or less the same thing when you posted. The DB25 is indeed wired DTE. Good reference!

Edited title for 'solved'
 
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