Modbus TCP with Beckhoff (Wago)

Hi,
I'm looking for examples/how to/lib/dll to build a communication to a Beckhoff BK9000(similar to Wago 750) which have a Ethernet - Modbus TCP Option.
I'm able to write via LabVIEW-TCP-Functions but only once after powering on and the result/answer is more confusing.
For the lookout OPC variant i heared there is still some additional software needed - true? or is it possible to set up the communication with lookout OPC without third party driver?
Thanks for any help
Hans

Hi JAMR,
There are plenty of examples that setup up the tcp server communications. If you open up the NI Example Finder and double click on the Networking Folder (under the Browse tab). You can then select the TCP & UDP folder and find several examples that use TCP. Also, there is a great knowledge-base article that provides information about network communication with TCP/IP messaging protocol. Essentially, what you are going to want to do is establish basic connectivity between the computer and the device and then assign the device an IP address. Before you do anything with the driver for the device, you might try to ping the device first. Once you can get this working, then you can set up the TCP/IP communication. I hope this helps!
Carla
National Instruments
Applications Engineer

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Using modbus/TCP with USB ethernet adapters

I have a test stand where I have a handful of USB instruments and a single modbus/TCP slave. I'm considering adding a USB ethernet adapter to the stand so that there is a single USB cable connecting the computer to the hardware rather than both a USB and an ethernet connection. Does anybody out there have experience (good or bad) using USB ethernet adapters with modbus/TCP slaves?
The existing USB instruments all use ASCII/SCPI-style command sets. The Modbus/TCP slave is an Automation Direct EBC-100. Nothing high-bandwidth or low-latency. Basically, the computer issues no more than a handful or command or request (ether SCPI or Modbus/TCP) per minute.
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Adam G wrote:
Hello Mark,
I was wondering what NI hardware you are going to be using in your application? Also are you going to be using LabVIEW for the programming? Have a great day!
Best Regards,
Adam G
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Problem communicating via Modbus TCP with Honeywell UDC3200

Hello:
I have to read the temperature of the Input 1 of this controllers. I've succesfully read the temperatures in the controllers. I'm using Modbus TCP/IP for the communication through the NI Modbus Library 1.1. I'm working on LabVIEW 8.5.1. However, sometimes when I open the connection, I get error 56 (timeout), despite that the controller responds to a ping. When I can initiate all the connections to the controllers, some hours after the monitoring has started, randomly, I get an error 66 (the connection was closed by the peer). This error interrupts the connection and the temperature readings stop. This is not acceptable.
Also, I've found out that if you don't request some data from the controllers in 5 seconds or more, also the error 66 appears. To solve this, I poll twice a second the controllers but the error 66 still shows up.
The controllers and the PC are interconnected via an Ethernet switch. The switch works well.
In brief, I can communicate with the controllers but the communication is not reliable. Sometimes when I start the communication I get an Error 56 and sometimes after the communication starts I get Error 66. It cannot be predicted when this will happen.
Why does the error 66 appears?
Has somebody communicated succesfully with this controllers?
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Using LabVIEW since version 7.0

Hello:
Thanks for answering Pedro. I've read the document you told me to, but it refers to problems with VI Server, the application is not using VI server, so I guess the problem comes from somewhere else. I still haven't figured out why this is happening.
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Using Modbus TCP I/O Server with new DSC Shared Variables in LabVIEW 8.6

Hello,
I'm using LabVIEW 8.6 and want to communicate with a Beckhoff BK9000 Ethernet TCP/IP Bus Coupler via Modbus TCP. Instead of using the NI Modbus Library, I've tried the new LabVIEW 8.6 feature "DSC Shared Variables" as described at the bottom of this page: Latest NI LabVIEW DSC Module Features and Demos. Reading of analog input bus terminals works fine. However, I haven't figured out yet how to write on an anolog output bus terminal with these shared variables.
It's about a 16 bit analog output and I need to write to the registers 0x1121 and 0x0801. It works with the NI Modbus Library (just using function code 6 and choosing the registers), but on the other hand I don't know which shared variables I have to choose for these registers. I've tried several data items (e.g. 400001 upwards as well as 402049 for 0x0801) but none of them worked. I would be glad for a short explanation - thanks in advance for your support!
Regards
utechle

The Beckhoff documentation says, that holding registers start with 0x0800. I've checked this by using the NI Modbus Library. I used the "MB Ethernet Master Query.vi" togehter with the function code 6 for "Write Single Registers", changed the settings of the starting address to hexadecimal view and entered 801 (since it starts with a control byte in 0x0800 and the data out word follows in 0x0801). Furthermore, I had to address register 0x1121 in the same way for resetting the watchdog. As I've mentioned in my first post, this method works fine. However, I haven't found out yet which shared variables i have to use for accessing these registers.
On the other hand, it's no problem to read data from analog input bus terminals using shared variables. They start with 0x0000 (status byte) and 0x0001 (data in word) and I can read data with the shared variable and data item 300001, respectively.
Message Edited by utechle on 01-27-2009 11:12 PM

Does anyone have Experience talking to a WAGO Ethernet Fieldbus copler using the Open modbus/TCP protocol and LabView ?

I have an Ethernet Fieldbus Copler of WAGO which supports the OpenModbus/TCP Protocoll, and I want to talk to it over LabView. Does anyone know how to do this or even has example VI's or Librarys ?

Wago and National Instruments have worked together to test and develop an application note showing the use of the National Instruments Modbus driver with LabVIEW and the Wago Ethernet Coupler. I have attached the preliminary applications note (which is in final technical review here at NI). You can purchase the National Instruments Modbus driver by ordering the Industrial Automation Servers, part 777616-01. The USA price is $995. It should save you quite a bit of time in working with the Wago device and any other industrial controller or modbus device you might work with in the future.
Preston Johnson
Business Development Manager
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444
Attachments:
wago_overview.doc ‏171 KB

Watlow PM with Modbus TCP

Hi community,
I have a watlow pm temperature controller connected to my computer with an ethernet cable. I need to communicate with the device via modbus tcp. I know for sure that the unit is functioning as if I use a modbustcp test program (see the first attachement), then I can read the temperature of the K type thermocouple which is connected to the unit. (the IP is 192.168.10.3, and I read two words from address 360). The temperature on the screenshot is 23.61992C
I would like to do this from LabVIEW by using an IO server. My problem starts at the beginning. I right click on my computer >> new >> I/O server >> Modbus
then in the popup window I select "Modbus ethernet" in the top right corner. I have attached this popup window. What is the Address in the communication settings section. The IP need to be entered at the bottom, so I have no clue what is the Address field is referring to.
Then I try to create bound variables... I see a huge list of registers, but honestly I dont understand how the address 360 I use in the standalone program translates to this list. Which one should I select from the list? Whatever I select gives me either 0 or FALSE if its a boolean. According to the documentation 360 is the relative address and the absolute is 400361. Actually there are a register list from 400001-465535, but if I select 400361-400362 I still read zero.
Reading only zeros and FALSE values... thats suspicious. Something is wrong.
Please help out with your thought!
Attachments:
modbustcp_OK.png ‏132 KB
modbus_config.png ‏56 KB
modbus_reg_list.png ‏98 KB

OK, just a quick (and dirty) test. Can you try this VI.
Kees
Attachments:
MB TCP test.vi ‏20 KB

How to comminucate with multiple PLCs with Modbus TCP/IP using dynamic multithreads?

I have an application in which I communicate with several PLCs using MODBUS TCP/IP toolkit. There is an array of IP addresses that the user can configure. Using for loops allows to work with this however if one PLC is out, the program waits for the timeout before polling the next PLC. I would like to use a multithreading type in order that all PLCs are polled at once and is not dependent of each other. In other words, I would like to dynamically simulate several while loops happening at the same time. Is this possible?
Thanks
arikb

arikb wrote:
Thanks A_Patel,
I thought of doing that but do I need to run this as a VI server in that case? How would I pass inputs and outputs of the subvi?
Appreciate the help,
arikb
Take a look at my Nugget on dynamically creating occurences found here.
Just ignore the Occurence stuff and the rest of the code and verbage should help you. The example code creates a bunch of background processes and passes a unique parameter to each.
Have fun,
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Ben Rayner
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Write values to PLC addresses via MODBUS/TCP

I am trying to write values to some addresses on a PLC connected to my computer with MODBUS/TCP. I've mapped the addresses that I would like to write to on my project's MODBUS library as shared variables. However, I seem to neither be able to read from nor write to them these addresses. I've tried viewing the variables in LabVIEW's Distributed Systems Manager and the variables, when configured as read-only or read/write, report an unknown value, and when configured as write only, they do not display a value.
I've verified that the PLC is connected properly, and I am able to read from other addresses on the PLC that I do not wish to write to. There also does not appear to be a communication error either. I have also successfully read from and written to the addresses using a third-party application, but for some reason, Labview will not do the same.
Any suggestions on what might be wrong?
Thanks!

Hello Griffon,
How did you set up your Modbus I/O Server? Did you follow the steps in this document?
Connect LabVIEW to Any PLC With Modbus
Make sure when setting up your server that you put in the IP address of your PLC (not localhost, or 127.0.0.1).
Also make sure that you're adding variables using the "create bound variables" dialog.
If you did set everything up in that way, and it still not working, can you clarify what you mean with this sentence?
"I've verified that the PLC is connected properly, and I am able to read from other addresses on the PLC that I do not wish to write to"
Does this mean that you can read values out of the PLC using modbus, just not the values you want?
Colden

Multiple Modbus Servers with Different Unit ID running in cRIO 9074. Possible ?

Hello
I want to create an application such that i can create two Modbus I/O slave server (TCP/IP) with different unit ID and can communicate with the slave through Clients. I created this application but only unit ID 1 is working. Is it like this that at a time two modbus slaves cannot work together ? Also I tried with one server and giving different Unit ID but then also it's not working. I found one thread, here is the link.
http://208.74.204.114/t5/LabVIEW/how-do-i-get-multiple-tcp-ip-modbus-to-work-together/td-p/2239130
Are there any updates on this issue.
Labview 2012 sp1
cRIO 9074

I don't fully understand your issue (but I'm trying).
Traditionally Modbus TCP/IP slaves cannot talk to each other, also the UnitID is mostly moot for MODbus/TCP since ports and IP addresses exist (unless you are building custom applications that will handle UnitID internally, because you have can't have 2 servers running on the same port).
If you can clarify your first sentence that would help a lot.
Varun_ECK wrote:
Hello
I want to create an application such that i can create two Modbus I/O slave server (TCP/IP) with different unit ID and can communicate with the slave through Clients.
You want to create 2 MODbus/TCP slave servers, that can talk to other slaves? Or do you want the Master to automatically do things based on the slaves response? Are the TCP slaves on different computers, IP, etc?

Modbus TCP server/slave implementation

Does anybody have experience to implement a modbus server or slave application? My computer needs to communicate with a PLC. The configuration is: computer is TCP server or slave, PLC is TCP client or master. Computer to write input registers for PLC to read. Computer read holding registers from PLC. Cannot find any labwindows examples.
Thanks a lot.

Thank you all for the replies. Most the links are for modbus tcp client (master) instead of modbus server (slave).
Now I am trying to use a modbus slave activeX control (trial version) from Automated Solutions Inc: http://www.automatedsolutions.com/products/modbusslave.asp.
I created an instrument driver using Create ActiveX Controller wizard. I can get a correct object (modbusHandle) with the first line below (status = 0). But the second function (set a property) gives negative status return (status = -2147418113).
status = ASMBSLVLib_New_DASMBSLV (NULL, 1, LOCALE_NEUTRAL, 0, &modbusHandle);
status = ASMBSLVLib__DASMBSLVSetDataMode (modbusHandle, NULL, ASMBSLVLibConst_DATA_MODE_MB_TCP);
Did I create the activeX control correctly? Automated Solutions told me that the ActiveX control is a windowless control. It's a runtime control. Is it a problem?
Thanks in advance.
jzhu0000.

MODBUS/TCP very slow execution

Dear all
We are new user to Labview and to LabVIEW forum.
We are designing a LabVIEW application that interacts with PLCs.
We are trying to exchange information between a PC/labview and a PLC. Both support the MODBUS/TCP protocole. We have designed the 2 programs easily, the PC/LabVIEW one being easily made with VI Library.
We first the PC/LabVIEW as a cleint and the PLC as server and it works perfect. It is quite fast as it takes less than 1 second.
We test the reverse configuration ie PLC as client and PC/LabVIEW as server. Of course we use different programs there and monitor the MODBUS/TCP frames with WireShark.
It works also but the execution on the PC/LabVIEW is very long (in the debug mode) : it takes 5 secondes to execute the Write Multiple Register function ( 2 data to write) to prepare the response frame and to send it back. It is very nice to see the animation on the diagram but why is it so long ? This long time frame is a very big problem for our application.
We re not sure to know where to dig in !
Thank you in advance for your help.
Regards
Thierry

It sounds like you need to learn more about the LabVIEW development environment if you were confused about the slow speed of highlight execution.
I would recommend looking at the online LabVIEW tutorials
LabVIEW Introduction Course - Three Hours
LabVIEW Introduction Course - Six Hours

MODBUS/TCP in CVI

Dear All,
I need help to write MODBUS/TCP coding to read data from a third party device.
The deveice is getting connected with help of "ConnectToTCPServer" function. But i am not able to get the data from the module. Any idea how to send the qurey and get the data.
regards,
Kumar.E

Hi Kumar,
I have a few questions that will really clear up a few things for me. Are you actually using Modbus or are you using the TCP functions in CVI? What are you trying to do, basically what do you want to be able to do? The actuall functions that you need to call should be in your device manual. Do you have this information?
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Regards
Krista S.
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National Instruments

MODBUS TCP Error 56

Hello,
I am having trouble with MODBUS TCP communication. I am trying to read the input registers on a master.vi after a slave.vi has written to it. Attached you will find my slave and master vi's. I have made sure I had the correct IP address, same starting address for master and slave, and also the same port number. The input register is array size 4 and I've also wired that in on the master for the quantity to read. Could someone please give me some pointers?
Greatly appreciated!
Attachments:
Master.vi ‏15 KB
Slave.vi ‏13 KB

I found my problem. I was missing the TCP communication in the slave.vi.
Thanks

Modbus/TCP Queries

Hi,
I am trying to use Modbus TCP to set the time / date on my cFP-2120
running Labview Real-Time 5.0.1. For this purpose I have set up four holding
registers that hold two single precision floats, one for the time (format:
hhmmss) and one for the date (mmddyy). The idea is that each time the Modbus Master writes to the holding
registers, the time / date of the cFP2120 gets set.
In my application, I have implemented Modbus communication
similar to the MB Ethernet Example Slave.vi, which came with the NI Modbus library
for Labview 8.2. This is also similar to the Modbus tutorial here. Essentially,
I am reading the appropriate Modbus holding registers using the MB Register
Manager.vi (also part of the Modbus library) and use their values to set the
controller.
The problem arising is that I set the controller time even
if the Master has not written to the holding registers, which results in
wrong times/dates. Is there a way to determine whether these holding registers
have been written to by the Master, so that I can react on it as soon as this happens?
Thanks,
Volker

Devin,
thanks for the response.
Your suggestion are a possibility, especially the first one.
However, as these registers are holding registers (read/write), I was hoping to also post to them the current time by the slave to be read by the master.
In case the time needs to be synched, the master posts the correct time to the same registers upon which the slave will update its time and again start posting its current time to these registers.
I realize that the easiest way to accomplish this would be to just use different registers for posting the time by the slave and have the holding registers reserved to be written to by the Master. In a previous implementation in C ( ... please forgive me) I used to listen to the traffic and parsed each message coming in in order to determine whether (a) my device was queried and (b) which function code was used for which registers. Based upon the info I decided whether to just send back the current time of the slave to teh master or take the incoming time value and set the time of the slave.
How would I implement something like this in Labview? Or am I better off just having different registers for reading from and writing to the slave?
Volker

Modbus IO with multiple ethernet ports?

Dear LabView experts:
My Labview system needs to communicate with three Modbus slave units (motor drive controllers with Modbus TCP/IP option installed) to send commands (speed reference) and read drive status (actual speed, output voltage/current/power etc). The PC has a quad-port Ethernet adapter with three of the ports connected via standard Ethernet cable to the three controllers. The three Ethernet ports on the PC have been given static IP addresses (192.168.1.10, 192.168.1.11, 192.168.1.12). The three controllers have been configured to give the Modbus slave options static IP addresses as well (192.168.1.20, 192.168.1.21, 192.168.1.22). I have also downloaded the NI Modbus library (version 1.2) and would like to use its VIs to perform Modbus Master Query operations. To do this, it is first necessary to open TCP connections to the three slave units using the TCP Open Connection vi, and this is where my problem comes in. How do I bind TCP Open Connection to use a specific Ethernet port (one of the first three IP addresses) on the PC ? Thanks in advance for your help.
VRA
Solved!
Go to Solution.

Hello Mike:
Thanks for your response. I should have browsed this forum a little more before sending the message out. You are right; one way is to restrict each Modbus-dedicated Ethernet port on the PC to a range or even a single port number (using Advanced settings), and use that port number in the TCP Open Connection vi to ensure that this connection will go out of that port. The other way is to use subnet masks as pointed out more than once on this forum; instead of using a subnet mask of 255.255.255.0 for all three ports (which would put them all on the same subnet), I could use a subnet mask of 255.255.255.192 which would allow for four separate subnets, then give the three PC ports IP addresses in the range 192.168.1.(2-62), 192.168.1.(66-126), 192.168.1.(130-190), with gateways set to 192.168.1.1, 192.168.1.65 and 192.168.1.129. The Modbus slave units (motor drive controllers) would then have to be configured with static IP addresses in the respective subnet ranges, so that a TCP Open Connection to that IP address would automatically go out on that subnet.
Thanks again.
VRA

Modbus TCP with Beckhoff (Wago)

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