Exstance no of Modbus communication

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• Deal with failure when using LabVIEW 2011 and DSC MODBUS communication

  I'm currently reading from operating records a PLC with MODBUS/TCP. I confirmed that the PLC will update the values and in response to a MODBUS communication correctly by using a third-party program called Modbus Poll. However, when I try to query the PLC using the LabVIEW shared variable engine, I am unable to read the values of the same addresses that I consult with Modbus Poll.

  My installation is simply to a PC directly connected to the controller via Ethernet without a router between the two. I'm using LabVIEW 2011 SP1 with the DSC module.

  I opened the Manager of distributed systems OR to display the State of all variables in the Modbus Library that I created, and I noticed that the ILO CommFail permanently the value 'true '. All other variables with a 'read' access mode signal "failure of process". I tried to restart the process and stop and start the local variable engine without success. I also restarted my computer several times to see if any services did not exist, but this does not appear to have solved the problem.

  Finally, I resorted to listening to communications on the network card I have the PLC connected via Ethernet using Wireshark and found that while Modbus Poll communicates with PLC, number of MODBUS and TCP packet is sent and received. However, when using only LabVIEW or the DSM OR communicate with the controller, there don't seem to be any communication on the network card.

  Something that may be interesting to note is that I could communicate with the PLC and to read values with the DSM just once, when I understood everything first what address I should be reading of. All of this has stopped working shortly after. Prior to this, 'CommFail' was not generally set to 'true' with my current setup. Thinking it was my firewall, I have since disabled my firewall, but this seems to have had no effect on the problem either.

  Any help on this would be appreciated.

  So, I thought about it. It turns out that the IP address of the server i/o MODBUS must be set to the address of the MODBUS slave, not the local computer. The address of the i/o MODBUS server is defined by the navigation in the Explorer window projects, expanding the variable engine shared library for MODBUS and right click on the server MODBUS (for example Modbus1) item and select Properties.

  In addition, the addresses seem to be shifted by + 1.

  Thanks for the tip so.

• Server I/O from the VISA against library MODBUS communication approaches

  I read several white papers OR on the various ways to interface with instruments of communication using MODBUS.

  On the surface it seems to me that the I/O Server is the fast and easy way to put up just to get something. Once I found this so I'll have to determine if I really need an interface more low level. It seems to me that, even with the I/O Server, you can get low level features. But this seems contrary to what white papers.

  Someone with a more in-depth experience & knowledge on this subject would be able to provide a brief explanation of this type of low level function, you can not with the server I/O?

  Also, what are the advantages/disadvantages to using a VISA interface instead?

  As a summary of basic - VISA is the interface on the serial port, allowing you to send and receive data, but not to interpret the data real meaning (layer transport). Both the e/s server and the MODBUS library is a layer on top of that - they use VISA internally to manage the main part of the sending and the reception of the raw data and focus on translating raw data into a meaningful form (Protocol Layer).

  If you use VISA directly, you need to add your own logic to translate the General commands modbus in the raw data, that includes the server for transmission and reception, like the server, MODBUS i/o library.

  In my opinion, the I/O Server requires authorization (DSC) and the MODBUS library is free.

• Test serial modbus communication

  Hello

  I would like to test server-serial communication modbus master running on the CRIO (9012) and the serial modbus slave server communication.

  Issues related to the:

  Is this possible? Two VI run simultaneously? If so, what am I doing wrong

  The CRIO is connected by ethernet and series with PC.

  

  Best regards

  
  

• Modbus communication with a piezoelectric dynamometer

  Hello..!

  I am a new user of LV and I try to communicate with a piezoelectric dynamometer in modbus RS232.

  After you install NI Modbus Library, I created a master VI with labview 8.6 using these libraries and I can get communication with scale, these values are added in the registry U32Bit 1 and it's good, if I press a load cell, I can see the values exceed. (from 0 to 65535). Now, I want to show on the front the weight in KG, as the decimal separator, for a proper interpretation of the value for my client, so I added a block table to unbundle that I convert a value with I32Bit (-32768 a 32768) with a flag, but I don't see not all values...

  I guess I did something wrong (conversion), I read a few KB, but I do not see a solution...

  Can someone give me a link or information to show me an example to convert this value... ?

  Thanks in advance for any help to...

  Configuration of master VI:

  Read now register

  Address starting 2012 (query to get the net value of the load cell)

  Quantity 1

  Slave address: 1

  RTU

  9600

  3 com

  parity none

  Can you post some examples of bytes you receive from the Modbus read and you expect that these values are?  It's probably just a matter of the right of casting, or the number endianism, or operation of scale that must be done.

• invertek modbus communication by car

  Hi all

  Seems modbus is a way to communicate with the disks for a long time. For me, and because we have a new machine equipped invertel drive P2 is new.

  So, after many emails between invertek I couldn't so much as to communicate with the reader with their software. Only her entry to go to modbus.org

  For their software, I use a converter usb rs485 and I use pins 4 and 5 (pc connection), but for modbus change for 7 and 8 (modbus)

  Join is the manual for modbus for the driver.

  My question is, what is the easiest to read VI (for now) of records and the way to the entrance. I need to input 03 (for reading), then the registration number?

  Please help for the first step, then I'll build the complete software (I have now installed modbus library)

  Thanks in advance

  cpalka

  
  

• with boredom Watlow PM 485 modbus communication

  I have a PM Watlow I see now at MAX and using EZ area code can get info manufacture of.  I also uses the Modbus in the add-on on Saphire series tool to try to write or read anything from him (for the first time) and I always get an error of 'time' out of the slave.  I tried to make a simple reading of VISA I found on some positions, and I get the same timeout error.  It seems that if I try something Labview I get this error.  I even tried writing Hex to the thing with the same results.  Can anyone throw me a BONE?

  There are a couple of free libraries.

  http://sine.NI.com/NIPs/CDs/view/p/lang/en/NID/201711

  https://decibel.NI.com/content/docs/doc-30140

• Modbus Communications 32 bit

  I'm programming an application LabView 8.5 and I need to communicate to a temperature controller Watlow via Modbus TCP.

  The controller uses 32-bit floating point.

  I know how to read two consecutive 16-bit registers to obtain a 32-bit word.

  My problem is that the addressing of the Watlow structure begins to register 400,000 and Monte from there.

  The NI Modbus Library (that I used on previous applications with different controllers Watlow) seems to support only 16-bit addresses.

  I can't enter the registry values higher than 65,535 for my reads and writes.

  How to read the registry values for the 'high-address' in the Watlow controller?

  4 to 40 000 is assumed. You don't actually enter anything.   If you look, for example, register 40 012, simply enter the number 11 as the address.  (As in LabVIEW, addresses start at 0)

• Data available via modbus

  This maybe isn't the best advice for this question, but I can't find where to ask. For sure some experts Modbus communication engineers using LabVIEW for development and so I hope I can find the answer. At the beginning, Modbus was designed to manage a small amount of data (coils and registers on serial communication). Nowadays ModbusTCP is very popular and so bandwidth is not a problem in general. I would like to know if the current use of Modbus (taking account of the major systems with hundreds of nodes) is always to share the small amount of data (almost stationary signals and i/o). Or now it is used to share, for example, forms of waves and dynamic signals in general? In this case could someone provide a link to some devices that shared dynamic signals via Modbus? Thank you

  VIX wrote:

  I wonder if now some devices using a set of registers to publish a waveform, for example.

  I would recommend against that.  It could if open to some interesting race conditions depending on how the modbus has been implemented.  Imagine a bunch of reading registers while the host has been updated of their.

  In short, Modbus was never to be a streaming protocol.  It is intended to the industrial control there where only the last value.  If you want that the waveforms of a device, look for one that will stream.

• Closing datos por en scada modbus

  Muy buen dia a todos.

  Estoy modificando UN SCADA in the empresa in donde trabajo pero el problema as hay are consta esta para trabajar con FIELDPOINTS, yo eliminate los fieldpoints u OPC powered through y con PLC of MODBUS TCPIP similarly o serial ABB. Comunicación is the prevalence, puedo leer y señales analogicas write y digitales pero el escollo librar trato're como VI individual intensification has the perfeccion, pero ago al of integrarlo hora of SCADA no works, me errores marca el as como modulo escritura y lectura modbus esta receiving characters no aceptados o things asi extranas, estos momentos estoy tratando crear a Subvi don't express pero no is como hacerlo , is that the of primero doy a tools y ahi in crear una nueva express vi, of doy NEW despues en CREATE from a VI selecciono mi VI y me appears lo siguiente:

  SE me hace porque mi vi tiene tickets extraño y salidas, in this case tickets las salidas St o o reels pero no be that pasa.

  También estoy intentando hacer algo con las share if is you can hacer algo pero tampoco, en so mi problema're than mi SCADA y MODBUS corran al mismo tiempo, tambien initiates include todo el vi in SCADA el plano y cuando llega el programa ahi flow to para todo, ahi is is, variables, supuse than era una structure while , is the altogether there are quick-witted pero solo is me da UN valor.

  Ojala me can help alguien esto is to give has a client unos dias UN y todo esta por eso paradox.

  Mucho thank knew tiempo, reciban a cordial saludo.

  ING. A. Abraham. Alfonseca Melendez

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  Hola Abraham, the advantage of
  comunicarte con directly los lugar por MODBUS FielPoints are that the communication
  haces el through pilot directly variables compartidas, ahora o
  con estos tambien you puedes Comunicar por MODBUS. Para con MODBUS communication
  Server i/o MODBUS to estas using el este esta LabVIEW RT o en LabVIEW DSC, o
  the MODBUS libreria utilizando estas. ?

  Ahora el error that you
  Genera el del VI Express are you porque VI not las tiene nada en contacts
  Terminal, an esto is refiere don't con as no tickets tiene y salidas. Ahora
  probably aqui no using screw Express, the utility of los need live
  Express General are building as despues con use en herramientas para
  Los programas mas than fr if a component in a specific en programa, y proven
  MAS well utility para el Worflow para el programa final.

  Ahora el problema aqui of
  No funcionen juntos can be much more than a problem of integration. Como so
  mencionas you colocas a Subvi, con a ciclo while inside of a VI, VI el
  main goes a detenido meet (o por lo menos el ciclo in el as metiste
  Este Subvi) terminen run one until. Quitar el ciclo Al solo everything is
  runs una vez cada vez lo controls has call desde el principal, so solo lo
  Mandas call una vez solo you will a dar UN dato.

  Ahora lo mas algo
  con el to use are simple as puedes hacer I/O Server in case of than cuentes
  El, there is what sets el I/O server variable ligar puedes compartidas has los
  looking for MODBUS, y como utilizarlos compartidas variables in you sistema
  SCADA.

  Estas ligas you pueden ser
  utility of:

  Connected LabVIEW has any red Industrial y PLC.
  Developer Zone - National Instruments

  How to turn an RT target in Modbus slave using i/o
  Servers - Developer Zone - National Instruments

  Connected LabVIEW has any red Industrial y PLC.
  Developer Zone - National Instruments

  Saludos

• Modbus

  Hello

  I'm new to Labview and am currently writing a code in Labview and I the Modbus communication protocol. I want to be able to send messeges through labview code and ask the inverters, which is connected to the PV modules, for give me data and he just send me the data. This will be a RS 232 communication.

  Where should I start? Please let me know if you know something about it.

  Donya

  Both ends enough to define the same thing. For the physical connection, you need a null-modem (tx and rx exchanged) cable.

  Why would anyone use series for communication between 2 pc instead of an ethernet connection?

• How to test the stability of the communication and to calculate ber using the CVI?

  Our Chief Engineer gave me a task yesterday. He asked me to make testing of software and to calculate the error rate binary we would like to know our stability of communication.

  However, I never touched this aspect of knowledge. I know a bit about the CVI and I want to write code with CVI bit error rate. So I could test the stability of the communication.

  But I don't know how to analyze and judge the receivers codes, whether they are good or bad.

  We use the Modbus communication protocol and receive data via a port series, so I want to back up all the data and record the total number of datas, marking as M.

  then, save the eligible data and save the number marking as N. Thus, the error rate is binary/m (M - N).

  If it's doable? Or you have a good idea. Thank you very much.

  unsigned char in_data[100]; 
  
   inqlen = GetInQLen (comport);
   for(i=0;i
  Above is my code that receives all the data I want to save the data [] array in_data and save the number.
  switch(inqlen)
  {
   case 19:
   {
     crc=usMBCRC16(in_data,inqlen );
     if((in_data[1] == 0x03)&&(crc==0)&&(in_data[0]==device_addr))
      {
  
      }
   }
  
  Above is the judgment of condition who receive eligible data which mark as N number.
  I know there is a prerequisite that I filter all the bad data. However, I don't know any good idea. I'd appreciate if someone could help me.
  Thank you very much.
  Best regards.
  xiepei
  			 
  		   

• problem of Modbus

  Hello world

  I'm trying to contact card ADAM 4024 (4 ch analog outputs). I use the Modbus communication. Please check the error Image I receive.

  Please explain the reason for the error.

  Thank you in advance.

  Hi LV_pro,

  Thank you for your response. It was very stupid mistake. The card has been configured for the "ADVANTECH" Protocol .  I changed it to MODBUS then my program is very well executed.

  Thank you once again.

• Lib Modbus OR LabVIEW 2014

  Someone sees that a problem with the NI Modbus Lib in Labview 2014 use is intended for the version of labVIEW 7.1 - 8, 6.  NEITHER directed me this way rather than the Module DCS since I use only Modbus communication and it's just a very small part of the Module.  It installed and appears on pallets of user very well the son and the way that you would except:

  

  However when I run the program, I have time reading registry vi.  the library example is as well, so I'm at a loss as to what could cause this problem.

  Hello

  Try this code snippet, you must have 1 in qantity you can read 0 and you must put in the header of the EMPA.

  Lars

• MODBUS RTU - problem reading Holding - myPCLab Novus records

  Hello

  I've tried for a few days to read the logs at Novus myPCLab (it uses the Modbus RTU Protocol). I used the DSC module both Modbus Library without success (it seems to connect properly but cannot read).

  I need to read the given current.

  Does anyone have an idea on what am I hurt?

  Here's my vi and modbus address.

  

  Through the DSC

  

  I used the address PLC to 'HR Inicial' and 1 'St number.

  Through the library

  

  

  I used the PLC address in "start address".

  You have created a connection that is configured to use a "unit ID" 0.  Slave never devices typically use a device number 0 which is considered to be a broadcast address.

  Check the address of the slave of your device.  So make sure that you use this number.

  I guess that you communicate with a device that behaves like a slave.  If so, you must create a Modbus master in your code.  With the new modbus communication protocol Subvi, you created a slave.  A slave cannot talk to another slave.

  Similarly, in your second picture when you use the older Modbus Library, you not connected any constant to the top of the SubVI WriteRead that defines the parameters of series of devices such as RTU and address of the slave, so she takes by default to 0.  Once again, a broadcast address.