RS 485 2 wire auto control echos back...

[Angelantoni]

Hi all

Am using NI- PXI 8423 board with 4 RS485 com ports, i need to use the com port in 2 wire mode, if i use TXRDY Auto control mode of operation the receiver still recives what i just transmitted. how is this possible?, because the document says that the receiver is disabled when transmiting data. and how do i solve this problem?

Thanx for the reply
Arun

[Angelantoni]

Hi all

To add to my query, i have some inputs. I just observer that the property setting of wire mode gives me an error. so the wire mode property is never set. the error given by LabVIEW is

Error -1073807360 occurred at Property Node (arg 2) in GEN-Send-Cmd.vi

Possible reason(s):

VISA: (Hex 0xBFFF0000) Unknown system error (miscellaneous error).

I have also configured the same property in MAX, advanced settings for serial port.

what could be the problem?

Thanx for the reply
Regards
Arun

[Angelantoni]

Also If i try Open VISA session from MAX on my ports it gives me error stating that i dont have enough previleges!!
. I just formatted and assigned new IP to that machine and still it gives me the same error.

Regards
Arun

[JoshuaP]

In order to change the wire mode the operating system requires that you have administrative privileges in some cases. Try logging on as the administrator.

-Josh

[Angelantoni]

Hi Joshua

Thanx for the reply, Actually I want to change the wire mode of a com port in remote system, RT system. From MAX if I go to advanced settings of the COmport and change the wire mode, the wire mode seems to change, but in my application if I check what is set, I get unknown type. I guess if I configure the RT system from a PC, that PC is given full rights to the remote system, is this correct? Or should I have to do any thing else to achieve this.

Thanx for the reply
Regards
Arun

[LoganS]

If you have added the RS485 port correctly, in MAX, go to Devices and Interfaces »» Ports (Serial & Parallel) »» COMx »» Advanced Settings, and select your desired transceiver mode. Then save your changes. Once this is complete you should be able to run a simple VI like the attached VI and verify the transceiver mode. I did this on an RT system and the transceiver mode that I set in MAX was the same that was read from this VI.

Good luck!

Logan S.

[Angelantoni]

Hi Logan

Thanx for the reply, I have already tried checking the wire mode using the property node from labview, atleast if not the wire mode set the property node should atleast give me what wire mode is set.
but i get the response as unknown, Am still stuck up with this problem. Is there any thing else i can check to solve the problem.

Thanx
Regards
Arun

[JoshuaP]

You might not have the proper VISA Server security settings. This would mean that you can change the properties in side the VI, but you wouldn't be able to change the in MAX. Open MAX, go-to Remote Systems, select your RT System, then Software and finally click on the NI-VISA 3.3 folder. Select the VISA Options tab on the bottom and then select the Security item under VISA Server. You will need to make sure that the IP of your host machine (the one you are doing this from) is located on this list. To add an IP address to the list Click Add, then type in the IP and then click in the blank area inside the box. You should then get the Save option at the top. Make sure you click save. In addition, you can use wild card characters to specify the IP. For example I add something like 12.3.55.* so any computer on my local subnet can access the device and I have noticed that my computer will sometimes change IP addresses.

One other thing that I would suggest is making sure you have the latest NI-Serial RT driver installed. This requires upgrading to at least NI-VISA 3.3 and then downloading the latest NI-Serial driver for RT which can be found at ftp://ftp.ni.com/support/ind_comm/serial/lvrt/. Copy the MSI file to your computer and run it. You will also need to install the new software to each RT Target. Note that currently the latest NI-Serial 2.5.5 will still display NI-Serial 2.5.4 on the monitor if you have one connected to your RT target.

I hope this helps out.

-Josh

[LoganS]

Have you tried reinstalling the VISA software on your RT target? Perhaps there's a problem with your installation.

Logan S.

[Angelantoni]

Hi Joshua


Thanks a ton for your help, the wire mode is finally working. I reinstalled the NI-VISA and serial from the link you had given and i changed the security setting of visa, now every thing seems to working fine.
But what i don't get is, with NI-VISA 2.5.4 also this feature should have worked, but it did not. I had even formatted and reinstalled all the software in my remote system.

Anyway now every thing is working and am happy 😄

Thanx again
Arun