• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Rs232 pinout "8 pin mini din" Help.

Thread starter #1
I have a Small serial printer "Verifone 250" the kind that are used to print a receipt at check out lane.
The rs232 connector looks like a "Mac 112c" type. But I see only 1 Gnd connection. ( Not 3 ). So I assume the pin-out is differant.
There Is "DS1489 Quad Line driver / DS1488 q line rec. " connect near the port. ( no Max232 like I was looking for ).
Anyone seen, are use the DS1489/88 for rs232 commuacations ! I need to just locate a TX / RX pin on the printer!


panic mode

Well-Known Member
Thread starter #3
This is the best that I can see how the 1498 / 1488 are connected to the mini din on the printer side.
I sure need help Finding the "RTS, CTS" pins. I assume that a RTS is a output data line from the 1488, and the "CTS" is an input to the 1489 .
I Thinking ( It HURTS ), but I assume that this printer has "RTS-CTS" handshaking.
Please feel free to give any suggestions !



panic mode

Well-Known Member
please also check what is connected to remaining pins of the minidin8 connector. GND should be easy to find but on non-standard connectors, there could be power present etc. this is something to be careful about so do now use minidin8 pins 1,2 and 8.

the RS232 signals are fine, you can take chances and simply try things (shorting is fine, RS232 spec permits this).

Just look at the signal direction (PC is DTE device so outputs on DB9 connector are pins 3, 4 and 7) and make sure that outputs go to inputs and vice versa. you will have to do some testing using trial and error.

so far you know that your cable will have pin DB9-2 (RX) connected to either pin 3 or 6 of the minidin8, pin DB9-3 (TX) will be connected to either pin 4 or 5 of the minidin etc. pin DB9-9 (Ring indicator) is probably not going to be used (this is for modem). Pin DB9-5 (GND) will go to whatever pin is GND on minidin8 (pin7).
Thread starter #6
Thanks "Panic Mode" I figured the Pinout!
I have attatch the new layout . It looks like the printer needs RTS/CTS hand shaking. So I jumped them on the printer side.
Well it will print the first line ( "Hello Steve", 10 ,13 ) at 9600 BBS. But nothing else!
The code from the micro should give me 4 lines! (Hello steve, have a nice day, Ok! , each on a new line) . But all I get is a "Hello Steve"! (new line) "Hello Steve" nothing else.. But it works with another serial printer..
Is this a buffer isiue?

panic mode

Well-Known Member
for a moment i tought printer didn't like to be called Steve and prefered Rachel :)

excellent job...
verifone 250

Hi, I have the same kind Verifone 250 printer. and made a cable as you gave here. The printer did print something and did stop after some print , but the printout were garbage. Please give me some hint. what's problem?
Do i have to connect pin1 or pin 2 of mini-din to somewhere?
the pinout of the adapter is below:
mini-din DB25
5 3
7 7
3 20
Thread starter #11
Dylink, I jumped Pins 3-4 inside the printer!
Are you your computer are a micro to send the serial string?
what are comm port settings ?
Hi, 1Steveo ,
I do not know what's the 'micro' thing. Say, I have an serial printer Citizen idp 3535 with a DB25 port which connecting to console. There is a PRINT button on the console. when I press the print button, it gives few lines report of correct status, and so on. I check the DB25, there are only three pins (3, 7, 20) got connected.So I made an adapter mini-din to DB25 according your layout here. No Luck. Could you please tell me how to test the printer with Micro? What's the OS and software?
Thank you very much. DYlink

Latest threads

EE World Online Articles