Cannot print to Okidata serial printer with Hardware Flow control


I have an Okidata ML 186 printer with a 25 pin female serial port. I cannot for the life of my get it working on our Digi Portserver TS MEI

I can successfully wire the printer directly to a 9 pin serial port on a computer (no Digi in the mix) with the following settings:

DB9 PC <–> DB25 Printer
2 (Rx) <–> 2 (Tx)
3 (Tx) <–> 3 (Rx)
5 (SG) <–> 7 (SG)
6 (DRS)<–> 6 & 20 (DSR & DTR)
8 (CTS)<–> 11 (CTS or SSD, I think)

That works with printer set to:
Ready Busy (not X-ON/X-off)
SSD- on pin11 for the Busy Line Selection
and the computer set to Hardware flow control.

BUT, I completely fail when converting this connection (or Digi settings) to 8-pin RJ-45 to 25-pin serial. Per various information sheets provided to me by Okidata, I’ve unsuccessfully tried the following pinouts with a goal of Hardware flow control (same as my above working example):

RJ45 Digi <–> DB25 Printer
1 (DSR) <–> 6 (DSR)
2 (RTS) <–> 5 (Rx)
3 (GND) <–> Shell
4 (TxD) <–> 2 (Tx)
5 (RxD) <–> 3 (Rx)
6 (SG) <–> 7 (SG)
7 (CTS) <–> 5 (CTS)
8 (DTR) <–> 20(DTR)

RJ45 Digi <–> DB25 Printer
1 (DSR) <–> Shell
3 (FG) <–> 1 (FG)
4 (TxD) <–> 3 (Rx)
5 (RxD) <–> 2 (Tx)
6 (SG) <–> 7 (SG)
8 (DTR) <–> 6 (DSR)

Both of the above RJ-45 pinouts fail for Hardware flow control, and I’ve also tested them using Xon/Xoff and adjusting the printer to use the RTS, DTR, and SSD Busy Line Selection. I cannot find a combo that works.

In the actual Digi configuration I’ve tried port defaults, realport, and printer configurations using 9600/8/N/1 in EIA-232 mode.

Nothing is working for me. What am I doing wrong/missing?

The example used with your PC shows the printer using Xon/Xoff (software), rather than hardware flow control.

The following knowledge base article contains tips for Okidata printers that you might find useful:

Here are the cabling pin-outs for printer connections:

If using hardware flow control, be sure you wire the hardware flow control pin being used on the printer (whether its SSD or DTR) to the CTS pin on the Digi connector.

Thanks for the reply userid. I created a cable according to the layout on your second link. It’s still not working for me, but I have many more questions…

1.) As a sanity check, when the 16-port Digi is connected to the PC, it adds 16 more COM ports on the computer. So I am printing to COM6 which corresponds to Digi port 4 where the printer is plugged into. Would that be correct?

2.) The Digi has a 10-pin loopback RJ50 plug plugged into a port on the digi which we don’t use and don’t have configured for any devices. Would that cause any problems?

3.)For the cabling guide you provided, it’s recommending that altpin be enabled. In my Digi’s web config, in the MEI settings for the port, the only way I can enable altpin (that I’m aware of) is to change it from EIA-232 to EIA-422/485 and checking the 4-wire option so I can finally check the ‘enable altpin’ option. Is this correct, or should I leave it on EIA-232? I ask because on our other two Digi portservers with printers, we don’t even have to config the ports for the printers and they work out of the box.

4.) In the digi config for this port, should the Port Profile be set to ‘Printer’, RealPort, or completely undefined?

-I am using pin 20 for DTR and then setting the printer to use “DRT- Pin 20” via it’s physical configuration switches.
-On the printer its DSR Input Signal is set to Active (other possible option is Inactive which I also tried.).
-Basically I am using the defaults on the printer as detailed on Page 37 here, except for switch 7 and 8 to ON, ON to use DTR over SSD.$FILE/ML186%20Users%20Guide.pdf