Invalid Attribute Specified RSlogix500 Explicit Messaging

[Mustache]

Hi All,

I am having an issue with explicit messaging. I am using a Micrologix 1100 and programing it with rslogix microstarter lite v8.3. The attribute(hex) I am having issues with is 0324H dec:804.

When I enter this attribute I get a "invalid attribute specified" error.

The realworld setup is mirologix1100 connected to a Keyence NU-EP1 ethernet IP module. The sensors connected are two FD-XA2 flow sensors. I have no problem receiving data from the NU-EP1 but the attribute commands are lower value hex.

After struggling for awhile I only get this error if I enter a hex which has a dec value higher than 255.

Keyence says I am set up correctly and Rockwell wont talk to me with out a tech connect account

Help me?

https://photos.app.goo.gl/hJCnFtZkNHjTpXov7

 

[Ken Roach]

Welcome to the PLCTalk forum community !

When you post screenshots, it's best to get them directly from your PC if you can (using the Snipping tool or similar capture), then trim them and attach them to your post, which allows them to be viewed inline.

So you're doing a CIP Get Attribute Single command (0x0E):

Class = 0x66
Instance = 0x01
Attribute = 0x0324

RSLogix 500 lets you enter C/I/A in either hex or decimal.

I noticed in your screenshot that you literally entered "0324H", rather than "0324". That might not make a difference because the software suggests it understands it by showing you the decimal equivalent.

What exactly is Attribute 0x0804 on that Keyence device ?

Have you tried reading that attribute with a different EtherNet/IP tool ?

It's possible there is no easy fix to this. I noticed in the Help file for the EEM Ethernet Explicit Message instruction that the ranges for Class and Instance are 0-FFFF, but for Attribute it is only 0-FF.

 

[Ken Roach]

More detail: the details of the RIX file, which provides CIP routing information, confirms that the Class and Instance can be 1 byte or 2, but Attribute is always 2 byte.

 

[Mustache]

Welcome to the PLCTalk forum community !

When you post screenshots, it's best to get them directly from your PC if you can (using the Snipping tool or similar capture), then trim them and attach them to your post, which allows them to be viewed inline.

So you're doing a CIP Get Attribute Single command (0x0E):

Class = 0x66
Instance = 0x01
Attribute = 0x0324

RSLogix 500 lets you enter C/I/A in either hex or decimal.

I noticed in your screenshot that you literally entered "0324H", rather than "0324". That might not make a difference because the software suggests it understands it by showing you the decimal equivalent.

What exactly is Attribute 0x0804 on that Keyence device ?

Have you tried reading that attribute with a different EtherNet/IP tool ?

It's possible there is no easy fix to this. I noticed in the Help file for the EEM Ethernet Explicit Message instruction that the ranges for Class and Instance are 0-FFFF, but for Attribute it is only 0-FF.

Hi Ken, thanks for the prompt reply!

To answer some of your questions:

- For the Keyence attribute see this screenshot:

You bring up an interesting option to use a different IP tool. What do you recommend? I see a post from you in 2015 you recommend softlogix 5800. Have you come across any alternatives since then?
http://www.plctalk.net/qanda/showthread.php?t=94533

I believe root cause is exactly what you stated about the Attribute range being only 0-FF. Below is the RIX data file I am using. Is there anything that can be done about the limited Attribute range? Is this a function of using dated RSLogix 500?

More detail: the details of the RIX file, which provides CIP routing information, confirms that the Class and Instance can be 1 byte or 2, but Attribute is always 2 byte.

 

[kamenges]

Are you looking for attrib 0324 or 0326?

Keith

 

[Mustache]

Very attentive Keith! Unfortunately have the same issue with 326. Anything over 255 gives me the "Invalid Attribute Specified" fault. Unless there is a setting or different message type which allows a range above 255 dec. for the attribute, I think I am out of luck with RS Logix500.

 

[kamenges]

My bad, Mustache. I didn't read carefully enough. I understand what you are seeing now.

Keith

 

[Ken Roach]

I see what Keyence did: they create one vendor-specific "NU Object" instance per connected device, and consider each parameter to be an Attribute.

Supporting our conclusion, I found this in the NU-EP1 user manual, page 5-13, and I believe that it also applies to MicroLogix:

The size of attribute ID used for SLC5/05 Series is 1 byte or smaller.
The SLC5/05 Series does not support the parameter which contains 2 byte attribute ID.

Do you have any other PCs or HMI devices in the system that have a CIP Generic Object driver ?

This may be a circumstance where CompactLogix is the appropriate choice. I don't think that Keyence makes a Modbus/TCP version of the NU device, even if you upgraded to a MicroLogix 1400 that can send Modbus/TCP messages.

A CompactLogix, even the little L16, could do this easily. But a bridge device that sends CIP Generic messages with a 2-byte Attribute number and also talks PCCC over CIP is surprisingly hard to find.

Rolling your own with a Linux SBC and Python is possible, but might be beyond what you want to do for effort/reliability.