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Old April 14th, 2015, 09:16 AM   #1
CAAJ
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Ethernet TCP/IP and Allen-Bradley CompactLogix (RSlogix 5000)

Hello All,

I am fairly new to PLC programming and really only know how to use the basic functions of RSlogix 5000. I have a new project I will be working on where the main goal is to interface a Weigh Scale and Pump using the Compactlogix controller. Connecting the pump to the system should be simple enough but, I am having trouble understanding how to connect our weigh scale to the system. We have the option of reading the Midrics scale using the Analog output card however we also have the option of using a Ethernet TCP/IP output card, which I hear can be more accurate and ultimately better for obtaining readings.

I guess my question is, how would I interface the scale to the CompactLogix controller using Ethernet TCP/IP, and how would I program this in RSlogix 5000?

Any response would help!

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Old April 14th, 2015, 09:59 AM   #2
Bullzi
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Welcome to the Forum!

There are a lot of questions on the forum about weight scales and PLC's. If you do a search I am sure you will find a lot of info.

I have never worked with a scale before but here is my opinion:
If the scale manufacture has a Add on Profile (AOP) for RSL 5K then the Ethernet is definitely the way to go. The AOP will automatically populate the tags for the different parameters of the scale. You just grab the ones you want and go.

If there is no AOP then it can get a little tricky. Being a new programmer you might then want to opt for the Analog method.

I am sure there will be more experienced people that post as well. Maybe if you give us the model of PLC and the Scale model there may even be someone that has already done it and would be willing to share their code.

Good luck!!
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Old April 14th, 2015, 11:11 AM   #3
jraef
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So can we assume your Weigh Scale output actually Modbus TCP/IP? The Ethernet medium itself is the same, and Ethernet/IP uses the same data structure as Modbus TCP/IP, so the only real difference is in the data packet format in your messaging. Most small vendors who don't know what they are doing will just default to Modbus TCP/IP because they already had Modbus RTU protocol for serial comms developed, so they just used the same basic packet structure and an Ethernet networking chipset.

If you want to get down into the nitty-gritty and you are a realy good programmer, you could possible do this on your own, or you can take the easier route and just go buy a gateway appliance, such as a Prosoft PLX31-EIP-MBTCP, or any number of other gateways out there that convert for you. They will change your data packet structure and prevent the MB TCP/IP from hosing up your E/IP network with superfluous traffic (although that's unlikely with a single device).
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Old April 14th, 2015, 04:13 PM   #4
CAAJ
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Quote:
Originally Posted by jraef View Post
So can we assume your Weigh Scale output actually Modbus TCP/IP? The Ethernet medium itself is the same, and Ethernet/IP uses the same data structure as Modbus TCP/IP, so the only real difference is in the data packet format in your messaging. Most small vendors who don't know what they are doing will just default to Modbus TCP/IP because they already had Modbus RTU protocol for serial comms developed, so they just used the same basic packet structure and an Ethernet networking chipset.

If you want to get down into the nitty-gritty and you are a realy good programmer, you could possible do this on your own, or you can take the easier route and just go buy a gateway appliance, such as a Prosoft PLX31-EIP-MBTCP, or any number of other gateways out there that convert for you. They will change your data packet structure and prevent the MB TCP/IP from hosing up your E/IP network with superfluous traffic (although that's unlikely with a single device).
With using one of these gateway converters, when attaching your device, does it automatically bring up all the necessary tags in RSLogix 5000 to control the component connected through modbus TCP?
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Old April 14th, 2015, 04:29 PM   #5
dmargineau
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I wouldn't use any converters but classic Ethernet Socket interface.

http://literature.rockwellautomation...t002_-en-p.pdf
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Old April 14th, 2015, 05:48 PM   #6
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CAAJ, I'd start by giving us the part number of the actual device you're working with, that way we know for sure whether we're talking Ethernet/IP or Modbus TCP/IP and don't steer you down the wrong path.

If it's Ethernet/IP its pretty simply (even if you don't have an AOP), if its Modbus/TCP there are the gateways that have been mentioned, as well as the Socket Interface that dmarineau mentioned (AB actually has sample code for using that with Modbus TCP/IP).

-Benaiah
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Old April 15th, 2015, 07:53 AM   #7
CAAJ
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Quote:
Originally Posted by benaiahhenry View Post
CAAJ, I'd start by giving us the part number of the actual device you're working with, that way we know for sure whether we're talking Ethernet/IP or Modbus TCP/IP and don't steer you down the wrong path.

If it's Ethernet/IP its pretty simply (even if you don't have an AOP), if its Modbus/TCP there are the gateways that have been mentioned, as well as the Socket Interface that dmarineau mentioned (AB actually has sample code for using that with Modbus TCP/IP).

-Benaiah
The Model Number for the Scale head we are using is YDO01M-EN. And after taking another look at the manual for this scale head, it looks like the output card is for Ethernet TCP/IP. Info on the product can be viewed here.

http://www.sartorius-intec.com/filea...O01M-...-p.pdf

If this trully an Ethernet/IP device, is it as simple as "plug & play"?

Thank you all for all the help thus far, the forum has been of great use for my first post!

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Old April 15th, 2015, 09:15 AM   #8
benaiahhenry
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Quote:
Originally Posted by CAAJ View Post
The Model Number for the Scale head we are using is YDO01M-EN. And after taking another look at the manual for this scale head, it looks like the output card is for Ethernet TCP/IP. Info on the product can be viewed here.

http://www.sartorius-intec.com/filea...O01M-...-p.pdf

If this trully an Ethernet/IP device, is it as simple as "plug & play"?

Thank you all for all the help thus far, the forum has been of great use for my first post!

Looks like that is actually a Modbus TCP device, not Ethernet/IP (see page 10 of the linked manual you posted under "Equipment Supplied").

So you could use one of the other gateways that have been mentioned (prosoft also has in chassis modules like this card that I think would work for you, I've never used one, maybe someone else can comment on how well they work), or you could go with Ethernet Sockets and do the modbus comms in ladder. If you want to go with the last option check out AB knowledge base article 470365 for sample code.
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Old April 15th, 2015, 09:23 AM   #9
CAAJ
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I will give this a shot!

Thank you very much all for your contribution.

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Old December 17th, 2015, 02:49 PM   #10
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Does anyone know if I can utilize Micrologix 1100 controller to read values from the scale mentioned above via Modbus TCP or Ethernet IP?
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Old December 17th, 2015, 03:05 PM   #11
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Micrologix 1100 have native support for Modbus RTU.

http://www.ab.com/en/epub/catalogs/1...unication.html

Quote:
Modbus RTU master and RTU slave; If you use RS-232C port and existing cables, an Advanced Interface Converter (1761-NET-AIC) and external power is required for networking. Modbus RTU networking is also supported directly using the RS-485 cable (1763-NC01) on this port.
However, you mentioned Logix 5000 and compactlogix above?? 1100 is programmed with Logix 500.
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Old December 17th, 2015, 11:35 PM   #12
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If you want to go with Micrologix and Modbus TCP/IP you will have to move up to the 1400.
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Old December 18th, 2015, 10:36 AM   #13
CAAJ
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Quote:
Originally Posted by harryting View Post
Micrologix 1100 have native support for Modbus RTU.

http://www.ab.com/en/epub/catalogs/1...unication.html


However, you mentioned Logix 5000 and compactlogix above?? 1100 is programmed with Logix 500.
Right, this is for a different application but similar concept.

Thank you for this reference!

Last edited by CAAJ; December 18th, 2015 at 10:51 AM.
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Old December 18th, 2015, 11:03 AM   #14
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From what I have read, Micrologix 1100 does utilize Ethernet/IP however only for messaging instances. First, could I use a gateway device from the scale to the processor's communication transfer? Second, through message exchanges, can I receive real time updates on measured weight values to perform other routines?
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Old December 18th, 2015, 12:46 PM   #15
Geospark
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Modbus is not Modbus...

Quote:
Originally Posted by CAAJ
Does anyone know if I can utilize Micrologix 1100 controller to read values from the scale mentioned above via Modbus TCP or Ethernet IP?
No, you cannot.

Quote:
Originally Posted by Bullzi
If you want to go with Micrologix and Modbus TCP/IP you will have to move up to the 1400.
Yes, you would.

Of the two MicroLogix controllers that have an Ethernet port i.e. the 1100 and the 1400; only the 1400 Series B supports the Modbus TCP protocol on its Ethernet port.

If you want to talk Modbus TCP, using Ethernet from a MicroLogix to the scales, then you must use a 1400 Series B controller.

Quote:
Originally Posted by harryting
Micrologix 1100 have native support for Modbus RTU...
Both the 1100 and the 1400 support Modbus RTU on their serial ports.

Note: Modbus RTU and Modbus TCP, also referred to as Modbus TCP/IP, are not the same protocol. Modbus RTU is a serial based protocol and Modbus TCP is an Ethernet based protocol. While their functionality is quite similar, their implementation is not.

Essentially, the Modbus TCP/IP command is a Modbus RTU command included in an Ethernet TCP/IP wrapper.

Serial based Modbus equipment will nearly always support the Modbus RTU protocol, but sometimes will support the Modbus ASCII protocol, or both. Ethernet based Modbus equipment will nearly always support the Modbus TCP protocol, but there are other, lesser used, Modbus Ethernet protocol implementations.

Your scales, if your using the same make again, has options for both serial and Ethernet communications. The Ethernet option has been confirmed previously as being Modbus TCP, but I don't know if the serial options support Modbus RTU, or not?

So...

If your scales is going to be talking Modbus TCP, then you would have to use the 1400 Series B for direct Ethernet communications.

If your scales is going to be talking serial Modbus RTU, or even Modbus ASCII, then you could use either the 1100 or 1400 direct serial communications.

For Ethernet, using an 1100, there is still the option of a gateway, or converter, as has been mentioned here, and as I now see you have asked about it...

For the 1100, you could use a Modbus TCP to Ethernet/IP gateway, such ProSoft's...

ProLinx 5201-MNET-DFNT

The data update rates will undoubtedly be slower by using Explicit messaging through this gateway to a Rockwell automation controller.

For the general readout of weight information, using the above is OK, but if you really need real-time data then using analog is probably the best advisable route to go here, if you are concerned with refresh rates and using stale data for a critical weighing/batching application.

The MicroLogix 1100 supports the addition of up to 4 expansion modules, including analog modules. The 1762-IF4 being the input module you would use.

Just some ideas to chew on while your "weighing" things up.
(Sorry, I couldn't help it! )

Regards,
George
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Last edited by Geospark; December 18th, 2015 at 12:51 PM.
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