Control Alicat PC through Labview

[tam_2407]

Hi,

MAX says that the COM port is ok, and there is no other program using the COM1 port; however, when I checked the COM1 port with a multimeter, while running a VISA-writing VI, there is no signal. What is it that I am doing wrong?

Sorry for asking many silly questions,

Tam

[Dennis_Knutson]

But I thought you got an error when trying to use the port? If that's the case, what are you expecting to read with the meter?

The blocking of the com port is a function of the OS. Something is happening that makes windows think that the port is being used and until that is cleared up, neither Hyperterminal or LabVIEW will be able to use it. Again, all I can suggest is going through the windows services being run. See if there is a modem program running.

[tam_2407]

Please tell me what to look for (name, code, or .***,....) I went to task manager. Is it the right place?

[tam_2407]

I try the COM port troubleshooting program made by Alicat Scientific. It says "Available ports:1" when the pressure controller is connected to COM1 port. Does this mean the port is not being used by Windows?

[Dennis_Knutson]

If their program can communicate and you still cannot start Hypertermina, perhaps it's their program that is running in the background or not releasing the port. I would recomend contacting the vendor.

[tam_2407]

When using Hyperterminal, if I enable the "detect carrier loss", Hyperterminal gives error "unable to open COM1 port.", otherwise it is connected but no communication. Please tell me what this means.

[Dennis_Knutson]

Where are you doing this 'Detect Carrier Loss'? That's not an option when you connect to a com port. Are you really trying to connect to a modem in your pc?

[tam_2407]

I try to communicate with the device through hyperterminal. The "detect carrier loss" is an option check-box when I create a connection. 

[Dennis_Knutson]

Not when I create a connection. Post your 'Connect To' screen with the "Connect using' selection box and the screen with the 'detect carrier loss'. A loss of carrier should have no application when you are directly connecting to a com port - only a modem. So, enabling it would be wrong and the error is understandable.

[AnalogKid2DigitalMan]

What we have here is a failure to communicate 🙂

1. Did you buy or make your cable?

2. Have you read the manual? See http://www.alicatscientific.com/documents/manuals/Pressure_Gauge_Controller_Manual.pdf

3. Is the instrument serial port set up to defaults?

Here is an excerpt from the manual on using Hyperterminal:

Configuring HyperTerminal®:

1. Open your HyperTerminal® RS-232 terminal program (installed under the “Accessories” menu on

all Microsoft®Windows®operating systems).

2. Select “Properties” from the file menu.

3. Click on the “Configure” button under the “Connect To” tab. Be sure the program is set for: 19,200

baud (or matches the baud rate selected in the RS-232 communications menu on the gauge) and

an 8-N-1-None (8 Data Bits, No Parity, 1 Stop Bit, and no Flow Control) protocol.

4. Under the “Settings” tab, make sure the Terminal Emulation is set to ANSI or Auto Detect.

5. Click on the “ASCII Setup” button and be sure the “Send Line Ends with Line Feeds” box is not checked

and the “Echo Typed Characters Locally” box and the “Append Line Feeds to Incoming Lines” boxes

are checked. Those settings not mentioned here are normally okay in the default position.

6. Save the settings, close HyperTerminal® and reopen it.

Hope this gets us going on the right path.

-AK2DM