ENG measurement and recording - 10 Channels

[Dr Vipin Seetohul]

Hello!

I have recently using LabView and am having lots of problem setting up a basic circuit (VI as is apparently called). Basically, i need to record the velocity of nerve signals over 10 channels and then save the data to disk(ASCII). How do we even create those channels? Do they have some sort of icons that we can add?? If i am posting in the wrong forum, can someone please advise me??? Thanks a lot.

Relevant details - Using: LavView 7.1; DAQCard-6062E for PCMCIA; NI-DAQ Software; SHC68-68-EP Shielded Cable; CB-68LPR I/O connector block with right angled connector.

[Riceman]

Use the DAQ Assintant to get the data. Configure the channels and type of data in it. It should be found in the Input Palette. If it is not there, reinstall your DAQ Board Drivers, and make sure you include the LabView drivers.

To save the readings to a file you may use Write to LabView Measurement File, found in the Output Palette.

If you need to treat the data before saving it, you will notice DAQ Assistant will give you one output independently of the number of channels. Use an Unmerge Signals (in the Signal Manipulation Palette). Resize the block to the number of channels you are reading. The order is the same as configured in the assistant. Then Merge Signals again before saving to the file.

Use the help for each block for more details. These are just some directions for you to start out. You will go gaining experience as you explore the help and palettes of your LabView.

Also, have you installed MAX (Measurement and Automation Explorer)? It has a valueble help for understanding the board configuration.

[Dr Vipin Seetohul]

Thanks indeed for the help. However i am still confused of how/where to connect the specific ports on the "write waveforms to file.vi". I have read and its quite obvious where to connect the 'error in', 'error out', and 'waveform' ports but what about 'file path', 'new file path', and 'append to file'. Do i just leave them? This is what error i get:

---------------------------------------------------------------------------------------------------

Possible reason(s):

Attempted to read samples that are no longer available. The requested sample was

previously available, but has since been overwritten.

Increasing the buffer size, reading the data more frequently, or specifying a

fixed number of samples to read instead of reading all available samples might

correct the problem.

Property: RelativeTo

Corresponding Value: Current Read Position

Property: Offset

Corresponding Value: 0

Task Name: _unnamedTask<88A>

-----------------------------------------------------------------------------------------------------

I hope you can please help me out.

Thanks.

Vipin.

Use the DAQ Assintant to get the data. Configure the channels and type of data in it. It should be found in the Input Palette. If it is not there, reinstall your DAQ Board Drivers, and make sure you include the LabView drivers.

To save the readings to a file you may use Write to LabView Measurement File, found in the Output Palette.

If you need to treat the data before saving it, you will notice DAQ Assistant will give you one output independently of the number of channels. Use an Unmerge Signals (in the Signal Manipulation Palette). Resize the block to the number of channels you are reading. The order is the same as configured in the assistant. Then Merge Signals again before saving to the file.

Use the help for each block for more details. These are just some directions for you to start out. You will go gaining experience as you explore the help and palettes of your LabView.

Also, have you installed MAX (Measurement and Automation Explorer)? It has a valueble help for understanding the board configuration.

5304[/snapback]

[Riceman]

File Path: is the whole path to the file where you want to write the data to. If you don't wire it, a File Selection Dialog will popup to ask that to the user.

Append to File: is a control input that decides wheter to Overwrite the contents of the file (or create it if file does not exist) everytime it's called or to append (add) the data to the end of the selected file. TRUE - appends to selected file; FALSE - creates or overwrites the selected file.

New File Path: is an output that returns the actual path of the file, in order to know which path was selected by the user in case File Path is not wired. If File Path is wired, New File Path will be equal to it.

When you click any input/output with your secondary mouse button, a floating menu appears. In this floating menu the is a submenu called 'Create'. In it you can create constants, controls, indicators for the input/output. If you select constant, it is always created with the default value of the input, so if you don't want to change that value, there is no need to wire it.

Are you using the DAQ Assistant? How are you measuring your data (one sample at a time, N samples, continuous)?

If you are reading One sample at a time you need to wire the output of your DAQ assistant to a Signal Collector (found in the Signal Manipulation Palette) in order to accumulate the samples you read.

Also, a good tool to find out what is going on is setting a breakpoint somewhere before the error occurs and check out what's going on using probes and step-by-step execution. To set a breakpoint click the block where you want with the secondary mouse button and select 'Set Breakpoint' on the floating menu. To add probes you can do it before running the vi in the same floating menu ('Probe') or by clicking on the wire when the VI is running. By any means, the probe must be added before the program flow passes (executes) the probe position. To step the execution look at the buttons in the toolbar of the block diagram when running.