METSYSTEM

DF1 and PLC5 vs SLC500

17 posts in this topic

Hi all,

Did a quick search in the forum to see if this has been asked before but couldn't see anything jumping out.

I have what appears to be an issue in making a third party RTU using a DF1 enabled RS232 port talk to a PLC5.

Background: The device talks seamlessly to a SLC500 with the CH0 set up as a standard DF1 Slave. I have replicated the setup like for like on the PLC5, I'm also happy that the cable between (the 25Way Sub) is as it should be.

Problem is, no data exchanges are happening, none of my PLC values are registering. The COMM light on the PLC5 is flickering periodically (almost as if its trying to periodically service a request from the master) but then times out. The RTU is scanning one N31 and one N32 integer so really small.

I recall (10 years or so ago) that when using a different telemetry device (Serck 2000M with PR27 DF1 card) I had to specifically set the PR27 to read PLC5 registers over SLC500 ones. This suggests that maybe there is an inherent difference between a PLC5 NRegister and a SLC500 NRegister??

I do not have the availability of setting my new RTU to scan PLC5 type registers so this may mean I am going back to the vendor. Before I do I was wondering if anyone here had come across this before?

Any advice would be awesome

Thanks

Alex

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Are you sure your communication parameters are correct.  It looks from your text that you are sure about the cable.  The periodic comm light flashing seems to me like a comm port that is trying to connect but not achieving a good connection.  Can you connect up a PC to this port and get online just to insure the cable and comm parameters are correct?

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Hi,

 

Yes, I used an RSLinx 232 driver and hit AutoConfigure to get online with the PLC5 so I could then set the IP address. Once I had that, I was online with the PLC through IP and able to try different settings on the CH0

Setting the Baud as low as 1200 (19.2k is the norm) meant the COMM LED just flashed a bit slower but no luck with the tag updates.

A point to note, the 3rd Party device was showing DF1 Comms Status as true, we just weren't getting any values.

Thanks

 

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Then you are probably down to settings in Ch 0.

Have to tried hooking the PC upto the 3rd Party Device and firing up a TelNet session or program to see if the data polling and message packets are being transmitted?

You could also hook up the the PLC5 and with Linx try the OPC test.

It would seem to me that a lot of these systems prefer the old PLC5 data structure and mapping versus SLCs or even Compact or ControlLogix.  I've have to map my tags to PLC5 data tables just to get it to work.

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Not sure if it's helpful, but look around page 125 or so of this manual:

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1770-rm516_-en-p.pdf

It looks like there's a difference between the DF1 drivers of the 2 platforms with byte vs word addressing.

Disclaimer: I've never dealt with this at this level, so this may turn out to be a wild goose chase.

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Thank you both,

The literature does seem to suggest some differences.

I will give it a whirl on the test bench and let you know

Cheers

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If you can post the program file for each PLC. (the .RSS and .RSP files)

A second eye might spot a difference in how the serial ports are configured.

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Just to add

I have used the below translation for my 9-25 end.

The Micrologix uses the 9pin terminals 2,3 and 5. I have just transferred this to the 25pin as 2,3 and 7

 

I have not linked the equivalent 4-6 or 7-8

Capture.PNG

Edited by METSYSTEM
Picture did not embed in text body

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Image result for db9 to db25 null modem cable pinout

Double check your pin-out for a null modem cable. (above)

Should be 

Pin 2 to 2

Pin 3 to 3

Pin 5 to 7

Edited by Mickey

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Thanks,

We have done this but still not helping.

I guess I'm back to the theory that the way the N Registers are presented in PLC5 are different in SLC500??

Any help would be really appreciated

Thanks

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My colleague just got a MicroLogix 1400 PLC talking to a PLC5 using DF1 via their serial ports. He used a straight serial cable with an in-line null modem adapter and a standard DE9-DB25 adapter.

He then used a pair of 9-pin prototyping breakout connectors with a 3/c cable that just used 2-3-5 with 2,3 swapped. The cable connected the MicroLogix's 9-pin connector to the 9-25 pin adapter on the front of the PLC5. Looking at a diagram from a manual, he thinks it would work with just 2,3,5 on the MicroLogix end connected to 2,3,7 on the PLC5 end, but we don't have any 25-pin breakout connectors to easily test that.

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I would think that even if the registers were different in the PLC5 versus SLC (ie swapped bytes or something), you would at least get a garbled number.  As I understand you are not getting anything.  That said, even though the cable he posted is wrong, he mentions getting online via RSLinx with autoconfig.  If he has been online with the PLC5 via his cable, then it should be correct. 

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Agreed, the cable should be correct.

If the registers are numbered differently enough (by byte instead of by element), the device may be trying to read non-existent registers. Not sure how the PLC would react to that. It may just return 0s or ignore the request.

 

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Thank you all for helping with this,

I have been on the phone with Rockwell today. We set up a DF1 polling master with my PC in RSLinx to prove the PLC5 and my cable.

You are absolutely right, it worked with the 2,3,5 to 2,3,7 cable.

The registers are correct. N30:0 (1element long) and N31:0 (1element long) are created in the PLC5 (just as they are in the SLC500) and this is what the 3rd party unit is configured to scan for.

Works on the SLC500 not the PLC5???

Anyway, all roads point to the DF1 driver in the 3rd party RTU and so I will be writing to the manufacturer to explore this further.

The thing that's niggling me is what I had to do in the old Serck 2000M. The PR27 card (DF1 interface card) had to be set to look for PLC5 registers over SLC500 otherwise it wouldn't work however, Rockwell assured me today that they are the same across the platforms so did not understand why that was happening.

Anyway, I will post back when I get an update

Cheers

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That's interesting...

I recently installed a CompactLogix processor to control some newer components as part of a system controlled by a PLC5. It's been working fine, but we decided to take it to the next level which requires passing a lot more than the 2-3 discrete signals. To save money and time, we added a ControlLogix chassis controlled by the CompactLogix via...

Ok, cut to the chase....

I set up MSG instructions in the CompactLogix to get information back and forth between the CompactLogix and PLC5. When configuring the MSG instruction, you have to select either "PLC5 typed Read" or "SLC typed Read". I wonder what the difference is...

Of course, this was over DH+, so it may be completely different...

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Joe yes, that is a very good point. I am aware of these different types.

If only I had that in my memory banks when on the phone to Rockwell!! I could have forced him to think a bit harder

I'll let you know how I get on in due course

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