Error with Eurotherm LV driver with the 2404

[russellb]

I am using the LV instrument driver, et24xx off of NI's website to communicate with a Eurotherm 2404 controller. 

http://sine.ni.com/apps/we/niid_web_display.download_page?p_id_guid=E3B19B3E971F659CE034080020E74861

However when the example program trys to read back a message from the controller the software returns the error "-1074001422" or xBFFC09F2 which according to the driver means "bad received message CRC".

However if I use Eurotherm's Sampler software utility I am able to communicate just fine with the eurotherm controller. 

I verified that my baud rate, unit address, number of bits, parity, stop bit, and resource name are the same between the LV driver and the Sampler software.

According to the readme for the LV instrument driver the driver was only tested with the 2416 and wanted to see if anyone had used this driver with a 2404 or if anyone has any ideas on what might need to be changed in the driver.

Regards,

Russell

[Andy F.]

Russell,

Usually a CRC error would indicate some framing error or possibly noise on the line.  However, this depends on the connection.  The Eurotherm Sampler Software connects through serial as well?  I looked through the et24xx drivers and was able to find the code that generates the error, but unfortunately that doesn't tell me much about why that error might occur.  The driver uses VISA to communicate, do you know if the Eurotherm software uses VISA as well?  Do you know if the controller you are using responds to message based commands, such as an ID query like *IDN?  If so we could test these commands using VISA communication in Measurement & Automation Explorer.  One last thing to check would be to make sure that you have installed the most up-to-date versions of the NI-VISA software just to ensure that is not the issue.  Hope this helps!

Regards,
Andy F.

[russellb]

Andy,

 Thank you for your help. However it turns out that the instrument was echoing back the command along with its response to the command. 

But the instrument driver was not accounting for the command being sent back.  Therefore to fix the problem I just read the command string first before reading the response to the command. 

Thank you,

Russell B   

[John Hoard]

There is another possible cause for this error message.  I am using the ET24XX drivers in a Labview program and got this message with a program that runs fine in another lab.  It turned out that I forgot to change the COM port from "4 wire" to "2 wire auto" mode in the COM port setup.  For some reason, instead of the COM port not working at all, I got the error message 1074001422 and some garbage values.