Re: How to use Digital output to turn on sensor for Analog Input?
Hello, Thank you for contacting National Instruments. If you are worried about the time of your acquisition being off, then you should associate each voltage measurement with a timestamp. This will allow you to know the exact time at which the sample was taken and you will never be off. You can use the Get Date/Time in Seconds.vi in our while loop with your AI code so that you can read a sample and read the time. You can than log the voltage value and the timestamp to your file. Regards, Bill B Applications Engineer National Instruments
Re: Answer to hardware requiremnts for controlling RH of air
Hello, More than likely you will need to put an equation in your application. Here is a simple example of how the application would flow: 1. Take a current measurement from the Omega using the FP-AI-110. 2. Use an equation to convert the current to units that are meaningful. 3. Use another equation to determine what voltage needs to be sent out to the MKS. 4. Use the FP-AO-210 to produce a voltage. 5. The MKS receives the voltage and does some action. You do not need to use Matlab scripts. More than likely, you can do all of your equation coding in LabVIEW by using the Math pallette or you can use a formula node and program your formula like C code. You may want to take a looks at some example programs that ship with LabVIEW for assistance. Go to Help Find Examples and take a look.
Re: Answer to hardware requiremnts for controlling RH of air
Hello, Thank you for contacting National Instruments. I will need some additional information in order to make a good recommendation on how to program this application. From your post, it appears that you would like to read the voltage from the RH sensor and send a voltage to the MKS using your FieldPoint hardware. Please let me know if this is incorrect. Here are my questions: 1. What FieldPoint Modules do you have? (ie. FP-AI-110) 2. What version of LabVIEW do you have? 3. What range of voltage does your RH sensor produce? 4. What range of voltage can your MKS receive? I look forward to hearing from you. Simply reply to this posting. Regards, Bill B Applications Engineer National Instruments
Re: How to get correct voltage reading?
Hello Astroboy, Thank you for contacting National Instruments. It appears that there is an issue with Advantech's AIVoltageIn.vi. If you are supposed to be measuring a 5V signal, and this VI is returning the number 0.09V then there is definitely a problem with either your DAS card or the driver that their VI is calling to return the measurement value. Unfortunately, there is really nothing you can do to correct this problem in LabVIEW other than try to scale the data to display correctly. Even in that case, you will need to know that factor of which the measurement is incorrect. More than likely you will need to contact Advantech in order to resolve the issue with the DAQ device. If you would like, you can check out our full line of Data Acquisition boards that will work seamlessly with LabVIEW. http://www.ni.com/daq Please let me know if you have any additional questions. If you get your hardware problem solved, I can help you with any LabVIEW questions you may have. Also, if you have any questions about our Data Acquisition boards, I will be more than willing to answer any questions. Regards, Bill B Applications Engineer National Instruments
Re: AOConfig buffer size
Hello Andrew, Setting your buffer size to be the same size as your array is typically what is done. The buffer size is not in bytes, but in samples. Please take a look at some of the example programs that ship with LabVIEW. Go to Help Find Examples Hardware Input and Output Trad. DAQ(LV 7.x only) Analog Output Generate Continuous Sinewave.vi. If you take a look at this VI, you will see that a sinewave array is produced using a FOR loop. This FOR loop generates an array that has the same number of samples as the buffer length input of AO Config. Take a look at this VI and see if you are able to modify it to fit your needs. In some cases, you may need to use a buffer that is larger than your actual data. This may be the case if your data array is generated dynamically and is not always consistent in size. The only size restriction in this case it that you are able to find a continuous section of memory that can accommodate the buffer. Let me know if you need additional assistance with this issue. The example programs should be a great reference. Regards, Bill B Applications Engineer National Instruments
Re: Is there a way to acquire a set number of points from multiple channels?
Hello, Thank you for contacting National Instruments. As Dennis had mentioned, there are many example programs that ship with LabVIEW that demonstrate how to take measurements from multiple channels with either a finite or continuous amount of data to be acquired. In LabVIEW 6.1 you can find these examples by going to Help Find Examples Hardware Input and Output DAQ Analog Input General. In these examples, if you would like to sample multiple channels, you simply need to add the physical channels separated by a comma for example: 1,3,5 would sample channels one, three, and five. You can also use a colon to sample a sequence of channels for example: 4:6 would sample channels four, five, and six. This makes it easy for you to choose the channels that you would like to sample without having to make any modifications to your code. Regards, Bill B. Applications Engineer National Instruments
Re: custom pulse train generation
Dave, Here are links to the user manuals for the PCI-MIO-16E-1 and the BNC-2110. These manuals should help you understand the signal connections a little better: http://digital.ni.com/manuals.nsf/websearch/06F1C9FB0D0BA5C286256C010057461B?OpenDocumentnode=132100_US http://digital.ni.com/manuals.nsf/websearch/7A862014CCE0CA0486256D3B005CE8DE?OpenDocumentnode=132100_US Regards, Bill B.
Re: 4-20ma output of ph controller connection to pc to monitor
Brett, I looked at the specs for the datataker dt50 and I noticed that it has a serial port interface. You may be able to send commands to the dt50 from LabVIEW and the dt50 may respond with data. You will need to get the command set from datataker. Here are some links to tutorials that explain getting started with serial programming: http://zone.ni.com/devzone/devzoneweb.nsf/Opendoc?openagent14A5CB349BD18D20862568210005EB0A#2 http://zone.ni.com/devzone/conceptd.nsf/webmain/C553228FD78A7ADD862568F9006E9129?opendocument http://zone.ni.com/devzone/conceptd.nsf/webmain/D48BA43C59B60277862569EE000501FD?opendocument There are also some good serial communication examples that ship with LabVIEW. Go to Help Find Examples Hardware Input and Output Serial Regards, Bill B.
Re: Can PCI-6601 be used to control a solid state relay?
Hello, A PCI-6601 may be able to control an SSR, but you must know the specs of the relay before you can be certain. The output voltage of the 6601's digital output line will be +5V with a source current of 4mA. This means that your relay must require no more than 4mA to turn on. Here is a link the 6601 User Manual. You can find these specifications on page A-1: http://digital.ni.com/manuals.nsf/websearch/DD0DBB6404BC139886256721007CF16D?OpenDocumentnode=132100_US If you think the board has enough current to power your relay, then you can make connections from the digital output lines of the board. These lines can be seen on page 4-2 of the manual. Regards, Bill B. Applications Engineer National Instruments
Re: When i run position measurement vi using 6602 continuous...
Nimal, I noticed that in your code, you have two while loops that are running in parallel. This is going to cause synchronization problems for one loop is going to dominate the other. Specifically, the loop with DIO Read will not allow the loop with DIO Write to execute until it has acquired all of the samples that it has set to read per loop iteration. A better practice would be to only have a single while loop and then cause data to be written by DIO Write and then have data read by DIO Read. You can connect the error cluster from DIO Write to DIO Read which will cause DIO Read to execute immediately after DIO Write. In your current application it is possible for execution to be stuck in one loop and rarely execute the code in the other. You may also be able to place delays in both loops, but combining them both into single loop would be the best. Regards, Bill B.
Re: SCXI Strain Null.vi throws -10005 error
RLD, You may want to try running the SCXI Strain Null.vi locally on the machine itself rather than through RDA. This will allow us to determine if the problem is local to the PXI-8146 or if it is being caused by a RDA Server communication breakdown. Regards, Bill B.
Re: 4-20ma output of ph controller connection to pc to monitor
Hello, Unfortunately, the RS-232 port cannot measure an analog current or voltage. We do carry products which will allow you to measure such signals. Please take a look at our Data Acquisition boards. Our boards are able to read analog voltages. You would simply need to connect your current to a resistor and then measure the voltage across the resistor with one of our DAQ boards. Here is a link to our DAQ boards: http://sine.ni.com/apps/we/nioc.vp?cid=1037lang=US Please let me know if you need any help selecting a board for this type of measurement. Note that these boards have multiple channels that you would allow you to monitor multiple sensors simultaneously in LabVIEW. Regards, Bill B Applications Engineer National Instruments
Re: SCXI Strain Null.vi throws -10005 error
Hello, Thank you for contacting National Instruments. The 10005 error is usually the result of wiring the wrong device number or incorrect channel SCXI string to the SCXI Strain Null.vi. Ensure that the device number you have connected is the same as the device number that appears in MAX for the RDA DAQ Board that is connected your SCXI chassis. Most importantly, ensure that you have connected the correct SCXI channel string to the SCXI Strain Null.vi. For example, sc1!md1!0 , would null channel 0 of module 1 of chassis 1. Please verify that both the device number and channel string that you have connected are correct. Regards, Bill B Applications Engineer National Instruments
Re: When i run position measurement vi using 6602 continuous...
Hello Nimal, Thank you for contacting National Instruments! The reason that you are experiencing this problem is because the Traditional NI-DAQ driver is single-threaded. Your Cont handshake input VI has a DIO Read VI inside a while loop with no wait. When this VI runs, the DIO Read VI will wait until it has acquired all of the Scans to Read and then will release the driver to be used by your position measurement. The VI will either read the number scans in the backlog or the number of scans to read. Since you do not have a wait, it is likely that the scan backlog is alway nearly zero. This means that the DIO Read VI will almost always be waiting for the total number scans to read before it releases the driver. You can do a couple things to alleviate this problem. 1. Place a delay inside your Cont. Handshake input VI's while loop. This will cause your backlog to grow. Do not use too large of delay for your scan backlog will grow out of control and overflow the buffer. 1 - 10ms should work fine. 2. The best way to solve this problem is to combine the two VIs into a single VI. This way, you can use the error cluster to control when things execute. You can have both sets of code in parallel and then snake the error cluster from the first set of code to the next. This will cause the DIO code to get configured first then the counter code and then in the loop, you would run the error cluster to the DIO Read and then to the counter get attribute to read the position. This would ensure that both measurements had equal time. The easiest thing to try is to decrease the scans to read in the Cont Handshake input and insert a delay in the while loop. Let me know if you are successful. Regards, Bill B. Applications Engineer National Instruments
Re: Digital I/O with multiple SCXI 1162 HV
Hello Randall, You can configure each SCXI-1162HV as a 32-bit port. This is cool because you can do a single read and acquire the status of all 32 lines. Since you have 4 SCXI-1162HV modules, you will need to configure each port and then you can read each port continuously in a while loop. If you are programming this in LabVIEW, you will need to have 4 VIs for configuring each port and 4 VIs in your loop for reading each port. You can also do this in DAQmx if you have LabVIEW 7.0 or other DAQmx supported software. Regards, Bill B Applications Engineer National Instruments
Re: Data Acquisition Question?
Hello, Here is a link to a simple Data Logger VI: http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DE0556A4E034080020E74861p_node=200082p_source=External 1. Download the zip file 2. Unzip the contents 3. Run the Simple Data Logger.vi 4. Choose your channels 5. Click Run 6. Name your log file (text file) 7. VI will begin logging data Hope this is what you wanted. Regards, Bill B. Applications Engineer National Instruments
Re: RDA delay
Hello, Thank you for contacting National Instruments. You have a couple options here. 1. Keep all of the processing on the server machine that is controlling the hardware. You should only have controls and indicators on your remote machine that will allow you to view the data and change parameters. In this example, you will have two VIs on that will run on the server and do all of the processing. The other will run on your client and you will view processed data and pass parameters to your server. You can use DataSocket to read and write data from your server VI to your client VI. 2. If the server machine is running Windows XP. You could just use the Remote Desktop Connection to logon to your server machine remotely. This would simplify things since you could just have one VI that would do everything on the server machine. Regards, Bill B. Applications Engineer National Instruments
Re: How to calibrate Quadrature Encoder signal
Hello, Thank you for contact National Instruments. Here are some links to documents on our website that should be very helpful for you in understanding your encoder and application. One of these links is even an example program for LabVIEW that you may be able to modify to do exactly what you need. http://zone.ni.com/devzone/conceptd.nsf/webmain/665470207873076386256B35007957A2?opendocument http://zone.ni.com/devzone/conceptd.nsf/webmain/4BAEC2BEE4C02FAD86256802007B8B5C?opendocument http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E5BD56A4E034080020E74861p_node=DZ52326p_source=External Regards, Bill B. Applications Engineer National Instruments
