modbus error 1073807194 with FTDI CHIP RS485

[jejmule]

Hi,

I am using modbus library  to control a Lumen temperature controller. The controller is connected trough  RS485. I am using a FTDI chip with VCP driver to interface this component.

The modbus transfer is in RTU mode.

On each step : 

I am reading the temperature on a device's register.

I am writing relay set point depending on time and consign.

My program is working fine during one hour (sometime 2 or 3 hour). next I have this error :

Error -1073807194 occurred at VISA Write in MB Serial Transmit.vi:7->MB Serial Master Query.vi:6->MB Serial Master Query Read Holding Registers (poly).vi->read-register-safe.vi->boucle-temp.vi

Possible reason(s):

VISA:  (Hex 0xBFFF00A6) The connection for the given session has been lost.

This error occurs during a reading period.

I attache the VI :

Boucle-temp-safe is the main program.

Read-register is the sub program generating this error.

I hope you could help, i am using this program to control the temperature cycle when i press ski (handmade ski build with friend). I have to set the set point manually for the moment.

[muks]

see this

[muks]

Also check this discussion

[jejmule]

Hello,

I think i solve my problem.

My usb transducer was buy on ebay with a ftdi chip.This transducer isn't stable in time (2-4hour).

I buy a new ftdi transducer on ftdi web shop and now it seem to work (22h). I have to test it on a longer period.

Thank you for help.

[muks]

Glad that you have figured it out.