Eurotherm 820 temperature controller control by LabView using RS422 serial communication

[Shahab_06]

Hi All,

I need to control a temperature controller (Eurotherm 420 model) with LabView, the communication is serial communication i.e, RS422. Can anyone help me in this regard?? Is the VISA for all type of serial communication same?? I'm using the Startech USB serial cable adapter (the picture is attached here).

Thank You,

Shahab

[RavensFan]

VISA is the same.  There is no inherent difference between using RS-232, RS-422, and RS-485 other than the adapters and the cables.  LabVIEW doesn't care which is which.

[mikeporter]

RS 422 and 485 only define the physical interface, pinouts, signalling levels and the like. One layer up, they all work the same: start bits, stop bits and all the rest -- a distinction that became very important in the early days of LabVIEW.

You see the original Macs didn't have RS232 ports. They had RS422 ports, which with a little creative external rewiring was often interoperable with '232 devices.

Mike...

[Shahab_06]

I'm trying to use a eurotherm 808 temperature controller driver which is available in the following NI site. But whenever trying to communicate the controller it's showing the error "Read timeout error, no data found at serial port."  Does anyone this sort of experience??  Highly appreciate your help.

http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=E3B19B3E90E4659CE034080020E748...

Thank You,

Shahab

[RavensFan]

Check your serial port address, your baud rate, start/stop/parity bits.  Check your cable.  Check the slave address used.

[mikeporter]

Also, it's been a while, but I seem to remember the 808 using a Modbus interface. Is that correct? If so, there are two flavors of Modbus: one uses binary data and the other ASCII data.

Mike...