PMDX Forum

General Category => Parallel Port breakout boards, motherboards, and dedicated accessories => Topic started by: phistrom on January 23, 2020, 05:56:33 PM

Title: PMDX-122 Replacement
Post by: phistrom on January 23, 2020, 05:56:33 PM
I have a FrogMill with two PMDX-122 controllers inside. I don't know much about them, other than they are controlled by the parallel ports on a Windows XP computer running Mach 3. The computer needs to be replaced (blown capacitors on the motherboard), but I see that Mach is discouraging parallel port control and their parallel port driver will not work with newer, 64-bit versions of Windows.

My questions are:

Can the PMDX-411 be used to control the PMDX-122 when using Mach 4 on a Windows 10 64-bit computer? (since I have two PMDX-122, can 2 PMDX-411s be used?)

Is there a drop-in replacement for the PMDX-122 that uses USB for control?

Are there better recommendations than that?

Unfortunately, I'm only the IT guy here, and not the operator of the machine. My knowledge of CNC and Mach is pretty much limited to "it's just what we have". I apologize if this is the wrong place to ask, or if I'm asking very stupid questions of the audience.
Title: Re: PMDX-122 Replacement
Post by: 12strings on January 24, 2020, 01:26:43 AM
The PMDX-411 will almost work as a direct PDMX-122 replacement**, but the 411 does not have a relay on-board.  If you need the relay, then you are looking at a PMDX-416 or PMDX-424.  Or a different PMDX board with an external opto relay.

** With Mach3 and 2 PMDX-122s, the 2nd PMDX-122  can be configured to have its 8 "data" pins (parallel port pins 2-9) as inputs the PC instead of the normal outputs.  The PMDX-411 cannot do that.  I don't recall if the Mach4 parallel port driver can also do that.

If you can list all of the signals that you use from the two existing PMDX-122 boards, I might be able to tell you whicih of the PMDX SmartBOB boards will work for you.
Title: Re: PMDX-122 Replacement
Post by: phistrom on January 27, 2020, 12:17:04 PM
Thank you for your reply and sorry for the delayed response.

For now I can provide images I took of the boards. (

I think I saw where to find the pin-outs in Mach 3 for the parallel ports, so I can provide you with those as soon as I can get back to that machine.
Title: Re: PMDX-122 Replacement
Post by: 12strings on January 28, 2020, 11:40:43 PM
Here is my best guess based on the pictures.  But if you can get a list of actual functions for each signal, that will allow a better answer.

From the pictures it looks like you have the following signals:

Left hand PMDX-122:
- 5 inputs (1 to "pin 10" on the EStop connector J6, and 4 J5)
- Relay N/O and COM terminals

Right hand PMDX-122:
- EStop switch on J6
- 2 inputs on J5
- 4 pairs of step/direction outputs
- 3 general outputs on J8 (parallel port pins 14, 16 and 17)
- Relay N/O and COM terminals

So in total that is:
- 1 EStop
- 7 input signals
- 4 step/dir
- 3 general outputs
- 2 sets of relay contacts.

Alas, there is no SmartBOB board that will get you 2 sets of relay contacts.  But depending on what you have those wired to, there may be a solution by adding an external solid-state relay or possibly using a PMDX-407 (see below).

From the SmartBOB comparison page (, either the PMDX-416 or PMDX-424 MIGHT work.  The PMDX-416 has 5 opto-isolated inputs and 3 non-isolated inputs, and 4 outputs.  The PMDX-424 offers 9 opto-isolated inputs and 3  general purpose outputs.  And both of these boards offer dedicated EStop inputs and a single relay.  With the PMDX-416, the 4th output might be able to be used to drive and eternal solid-state relay to supplement the single on-board relay.

Now if some of those output signals are driving spindle control signals, then adding a PMDX-407 to either of these SmartrBOB boards *MIGHT* get you the necessary number of outputs.