Do all PLCs use the same 8 pin mini DIN?

That is, do all PLCs that use 8 pin mini-din for connection to PG use the same 8 pin mini DIN?

In case I'm using non applicable terminology, I will state my question in these terms: I know of Micrologix, IDEC, Twido, Mitsubishi FX, et. al. (what am I missing?) and some various HMIs use an 8 pin round connector. Are they all the 8 pin connector known as "8 pin mini-DIN" described by Deutsches Institut für Normung? Could I buy a dozen of these 8 pin mini-DIN connectors and expect to be able to roll my own programming cables in the field for each and any of these 8-pin PLCs? Or would I find that some of them are actually not the standard 8 pin mini-DIN, but are some stupid "special" proprietary 8 pin connector?

If any of them are "special," which ones are they?

The Micrologix connector is a proprietary design. A standard mini-din will not plug into it. Automation Direct sells a cable that does fit the Micrologix (LINK), but it is not fully populated. It only has the 3 wires needed for communication.

I have used standard mini-din plugs with the FX, and (I think) IDEC. I can't say yes or no about the Twido.



-Eric

If more than one manufacturer who uses the same 8 pin DIN connector has compatible pin configurations it would be by accident.

RussB said:

If more than one manufacturer who uses the same 8 pin DIN connector has compatible pin configurations it would be by accident.

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That is an important point, Russ... I didn't mean to imply that the pinouts would be the same, just the physical mini-din plug.

I used to use the Cinch MDC-8PO5 cable when wiring FX PLCs to HMIs. For Micrologix, I usually bought the A-D cable and chopped off the DB15 end.



-Eric

Mini-DIN8 has a lot more variation than "RJ45" or "DB9".

The shell position, locking type, pin location, and keying plugs can all be different.

Even within Allen-Bradley, I can think of three Mini-DIN8 implementations; MicroLogix Channel 0, DH+ peer connection (PLC-5, SLC-5/04, 1756-DHRIO) and SCANPort.

None of those will physically fit into one another, and that's intentional because they are all electrically different and you could interfere with or damage the electronics on one by plugging in something different.

Ken Roach said:

......Even within Allen-Bradley, I can think of three Mini-DIN8 implementations; MicroLogix Channel 0, DH+ peer connection (PLC-5, SLC-5/04, 1756-DHRIO) and SCANPort.

None of those will physically fit into one another, and that's intentional because they are all electrically different and you could interfere with or damage the electronics on one by plugging in something different.

Click to expand...

Such a shame they didn't apply the same philosophy when they put a standard RJ45 on the front of 1756 ControlNet modules... "now where can I plug my EtherNet cable?" ... oops!!

Ken Roach said:

Mini-DIN8 has a lot more variation than "RJ45" or "DB9".

The shell position, locking type, pin location, and keying plugs can all be different.

Even within Allen-Bradley, I can think of three Mini-DIN8 implementations; MicroLogix Channel 0, DH+ peer connection (PLC-5, SLC-5/04, 1756-DHRIO) and SCANPort.

None of those will physically fit into one another, and that's intentional because they are all electrically different and you could interfere with or damage the electronics on one by plugging in something different.

Click to expand...

That's just downright irritating.

Even one manufacturer can't even get on the ball with itself, much less manufacturers get on the ball with each other.

Everybody's gotta have their own "oh-so-special" cable that they expect you to pay some outrageous price for. Drives me up the wall!

strantor said:

That's just downright irritating.

Even one manufacturer can't even get on the ball with itself, much less manufacturers get on the ball with each other.

Everybody's gotta have their own "oh-so-special" cable that they expect you to pay some outrageous price for. Drives me up the wall!

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Did you miss the part about the incompatibility being intentional to prevent damaging the devices?

Seems like a smart move to me.

rdrast said:

Did you miss the part about the incompatibility being intentional to prevent damaging the devices?

Seems like a smart move to me.

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No, I didn't miss that part. I just don't think that answer is good enough (coming from Allen Bradley, not Ken - I appreciate Ken's answer). Why couldn't they have designed all of their devices to use the same comms protocol, interface hardware, plug style, and pinout? Going back to day one of the desgins of these devices, is there really any good reason why the design team chose to make the devices in such a way that can't be compatible? Don't you think they could have made them compatible if they wanted to?

I don't know, seems obvious to me. The protocols was designed for different applications and talk to different type of devices; ie. peer to peer, RIO, etc...

harryting said:

I don't know, seems obvious to me. The protocols was designed for different applications and talk to different type of devices; ie. peer to peer, RIO, etc...

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I was talking about programming cables specifically. PC to PLC connection. I didn't read Ken's post closely enough and didn't realize he was including things other than programming ports. Thats why I got excited; wouldn't it be silly if AB had 3 different varieties of 8 pin round programming cables?

Also, not mentioned is that Automation Direct uses 4 or 6 pin telephone style plugs, Omron uses a serial connector, Telemecanique Quantum uses a different style (I can't remember what), etc. There are so many different brands and I've not found any that use the same cable. That's why half of my laptop case is taken up by cables.

You can use a regular MiniDIN-8 cable on a Micrologix. You just have to push it in firmly with a wiggle - it digs grooves in the plastic. It holds very securely and doesn't affect its ability to work with the expensive "specialty" cable.

strantor said:

No, I didn't miss that part. I just don't think that answer is good enough (coming from Allen Bradley, not Ken - I appreciate Ken's answer). Why couldn't they have designed all of their devices to use the same comms protocol, interface hardware, plug style, and pinout? Going back to day one of the desgins of these devices, is there really any good reason why the design team chose to make the devices in such a way that can't be compatible? Don't you think they could have made them compatible if they wanted to?

Click to expand...

Could they? Sure, but there are limitations. RS-232 Serial arguably "Could" be the standard, but it is not compatible with multi-drop installations. RS-485 type communications are, but then you still have the issue of 2 wire vs. 4 wire, and are limited in the number of drops/distances, and speed.

RIO was designed primarily to handle exactly that, Remote I/O, in the most efficient way possible, with the least processor overhead.

DH+ can handle remote I/O, but it is designed more to talk directly to the PLC processor, and HMI interfaces, whether they be the old single line message displays, or full blown PC Based HMI's.

Ethernet was just showing up when the PLC-5's ruled, and the original PLC-5 Ethernet connection was the AUI port that required an interface to either twisted pair (8P8C, NOT RJ45) or coax (10baseT, 10base2, or 10base5).

Pick a standard, any standard. Technology moves on, and maintaining backwards compatibility on a hardware level is very near insane. Would you even consider flashing a ControlLogix processor over a 19.2 kBaud serial connection? I know I wouldn't, unless I wanted a shiny new brick.

You may as well complain that you need different programming packages for each processor platform; Why isn't everything still based on the Modicon 084? Or the attempts of AB with the PDQ 2 or the PMC? If that was good enough in the late 60's early 70's, why isn't it good enough now?


You may as well ask why I have a 2012 Prius, a 1994 Surburban 1500, a lawn tractor, and a jet-ski. While they are all modes of transportation, they all serve different purposes.

That is why there are so many OTHER communications methods out there, and only (relatively) recently have there been cross-manufacturer standards.

RussB said:

If more than one manufacturer who uses the same 8 pin DIN connector has compatible pin configurations it would be by accident.

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I have studied this... I thought about trying to make a 'fit everything' cable with some sort of black box

I sell 64 different cables and only two are the same, one other is very close Allen Bradley PLC-5 1784-CP10, Automation Direct D3-DSCBL-2 and Omron C500-CN221-EU are all very close to the same.

The issue with the min din 8 and the CPU's listed is that (other then the pin out configuration) the protocol is also different the Micrologix is RS232, IDEC and Twido are both RS485 and Mitsubishi FX is RS422 so even if they fit and the wires were landed on the correct pin the com's would still not work or you would need a switch to change the protocol signal