AB PLC5/10 programming connection

technolog

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We have an old machine that we need to get running. It has a PLC5/10 processor with a DE9 9-pin DH+ (I believe) connector for programming. I've done a little googling and think I need a 1770-KF2 module and I'll to make up a couple of cables to connect it to the DH+ and the PC (via a USB/serial converter). Can anyone confirm if this will work or if there is a better solution? I've seen the 1770-KF2 modules on eBay for around $30.

PLC5 manual (p70)
https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1785-um001_-en-p.pdf

1770-KF2 manual
https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1770-um521_-en-p.pdf

Data Highway cabling installation manual (page A-8 has details of a KF2 to PC cable
https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1770-um022_-en-p.pdf
 
Yes, the 1770-KF2 is a suitable way to connect to the DH+ port on a PLC-5/10. Set them up for separate Node numbers and connect them with a piece of the appropriate Belden "blue hose" cable, with 150 ohm terminating resistors.

RSLogix 5 will support all the PLC-5 models with RSLinx Classic and Windows XP and later. Older software success may vary.
 
Thanks Ken. How vital is it to use the 'blue hose' for such a short length? We don't have any and we'd only need a foot or two. Could we just use some shielded twisted pair?

** EDIT: For completeness, the processor is a 1785-LT4/A series A firmware rev P**
 
Last edited:
Thanks Ken. How vital is it to use the 'blue hose' for such a short length? We don't have any and we'd only need a foot or two. Could we just use some shielded twisted pair?

Any conductor should work.... I remember Ken talking about using barb wire for a test one time and it worked
 
The PLC5/10 has an RS232 Serial port for programming on the front
That would be the easiest way if you have access directly to the front
Logix 5 software will work if you have it. also the older DOS version of PLC5 should work but it only runs in DOS ( Windows XP or older)
 
The PLC-5/10 is a "PLC-5 Classic" and the DB9 on the front is connected in parallel to the Combicon-style 3-pin DH+ connector. These were built before DB9 was commonly used for serial ports.

The PLC-5 Enhanced, Ethernet, and ControlNet controllers have a 25-pin serial port on the front. That family includes the similar-capacity PLC-5/11 controller.
 
For a short length, any twisted pair should work. For best results, do put the termination resistors in place, but DH+ earned its reputation as the most robust industrial network of its era.

This does sort of beg the question of whether it's wise to put a PLC-5/10 into service for a machine of any importance, but if you've got the software and the experience, I suppose there's no reason not to.

But while you're at it, get a hard-copy of the program and examine the I/O wiring schematics carefully, because eventually you'll probably want to migrate to a new controller.
 
For a short length, any twisted pair should work. For best results, do put the termination resistors in place, but DH+ earned its reputation as the most robust industrial network of its era.

This does sort of beg the question of whether it's wise to put a PLC-5/10 into service for a machine of any importance, but if you've got the software and the experience, I suppose there's no reason not to.

But while you're at it, get a hard-copy of the program and examine the I/O wiring schematics carefully, because eventually you'll probably want to migrate to a new controller.

We're a reseller of industrial machinery. We get all kinds of stuff that's past its sell-by date but the suits take the decision on whether we're replacing the control system and on this one, at the moment, if we can get it working, we're not.
 
This technote covers the basics in getting connected to a 1785 PLC-5 controller...

50288 - I can't go Online with my Classic PLC-5 Processor
Access Level: TechConnect

It describes the two ports and how they are internally linked and that they are both intended for DH+ communications only.

It lists the interfaces, including the infamous 1770-KF2.

It explains how to set the dip switches for the node addressing and the network termination where the controller will be an end node, such as the intended point-to-point connection here.

It mentions the fixed baud rate of 57.6 kb for the controller.

It mentions how you must *insure* that you use blue hose cabling to the 3 pin port (or barb wire!).

I still have a 1784-KTX PCI card powered in an old terminal PC here that's always left on. They interface with DH+/DH-485 or RIO. It always works whenever I need it, which admittedly is next to never these days.

Regards,
George
 
Thanks, George and everyone else who offered assistance. I've ordered a KF2 from eBay and will be trying to connect some time next week. I'm sure you'll be hearing more from me then :)
 
Could someone confirm my 'blue hose' cabling proposal, please?

The PLC5 has a preexisting connection from its 3-pin terminal block to a PV550 HMI via some DIN rail-mounted adapter. I'm proposing to connect my blue hose programming cable from the PLC5's 9-pin port to the 15-pin data highway port on the KF2.

PLC5/10 9-pin:
Pin 5: Blue wire
Pin 7: Drain wire
Pin 1: Clear wire

KF2 15-pin:
Pin 6: Blue wire
Pin 7: Drain wire
Pin 8: Clear wire

One thing I'm unclear of, do I have to connect 150-ohm resistors across the blue and clear wires at both ends?
 
Ha! Don't you just love it when something works first time!

I made up a blue hose cable, as described above. I made it 10 feet long as I read in one of the several manuals I downloaded that the length should be between 10 and 100 feet. I didn't use any 150-ohm resistors.

I also soldered up a cable to match the AB 1784-CP5 cable to go from the 1770-KF2 25-pin port to my USB serial converter.

The DIP switch settings on the 1770-KF2 were set to:

SW-8 RS-232-C

SW-1 Full duplex / BCC / Parity None / No embedded responses

SW-1-3 Detect & ignore duplicate messages

SW-1-4 Ignore handshaking signals

SW-2, 3 & 4 Station # = 005

SW-5 Network Link Baud Rate = 57,600

SW-6 Asynchronous Baud Rate = 9,600

SW-6-4 Pass through diagnostic command

SW-7 Peer communication link

The trickiest thing was finding the right driver to use in RS Linx Classic. Initially I was assuming I needed a DH+ driver but eventually I noticed the mention of 1770-KF2 in the DF1 driver dialog. I set the dialog box options to match the setup of the 1770-KF2 and I walked right in there! Downloaded a program and put it into run mode. Happy times!

Unfortunately, we still have quite a way to go until the machine is running. The PLC5 had lost its program and all we had was a paper listing. I've retyped it into RS Logix 5 and that's what we downloaded. Sadly, the Main file includes a JSR to U:3 and we don't have a listing for U:3 :(

I think U:3 is probably code to control the AB servo drive. So, next week we'll be digging into that and trying to get the machine running. Luckily the machine isn't too complex - T-Drill TCC-45 tube cut-off with a servo drive on the feed rolls and a measuring wheel encoder.
 
Well done in getting over that hurdle and good luck over the next.

Just a quick mention on you not having used terminating resistors - Both the 1785-LT4 and the 1770-KF2 provide built-in DH+ network termination. Once configured correctly there is no need for separate resistors to be added to the wiring for this basic point-to-point connection.

G.
 
Working with DH+ and RIO many years ago, in our Simulation/CAT area we nearly always connected up with plain vanilla 3-core mains cable, and no resistors that I can remember.


The cable runs were short, and it wasn't a "noisy environment" (except for the occasional cursing of some programmers when they discovered they made a bad mistake some time previously, and re-doing the software correctly would be a pain).


Got away with it every time. Yes, the DH+/RIO networks were extremely robust and weren't at all phased out if you got the conductors reversed....



On a side note - does anyone know why the conductors of the Blue Hose cables were reversed when switching from DH+ to RIO ?


Was it just simply that you could tell what the cable was by looking at the terminations ??
 
Well done in getting over that hurdle and good luck over the next.

Just a quick mention on you not having used terminating resistors - Both the 1785-LT4 and the 1770-KF2 provide built-in DH+ network termination. Once configured correctly there is no need for separate resistors to be added to the wiring for this basic point-to-point connection.

G.

Thanks George. I'll try to remember that, but my age combined with the infrequent nature of the probable usage of the information almost certainly means I won't :-(
 

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