01-11-2011 06:19 PM
Hey Everyone,
I have an ESPEC humidity chamber that uses a Watlow F4 controller. I am using this to run environmental tests on a device. Ideally I want to monitor the conditions inside the chamber and my device in the same VI. So far I have been having trouble communicating with the chamber using labview. It is using a serial port on the chamber and a serial to USB converter on the PC side. I have created a small Vi that will just act as a chamber monitor for me. I have attached the monitor VI below. It doesn't sense the chamber at all and give me the set points or current conditions. Any help you guys can give would be greatly appreciated!
Regards,
PChemist
Solved! Go to Solution.
01-11-2011 11:08 PM
Assuming it fails the init function, what error code do you get? Are you sure you are using the correct serial cable (null-modem or straight-through)? I don't have the driver. Where do you set the com port (baud, parity, etc.)?
01-12-2011 10:43 AM
Thank you for helping me solve this.
I am using a USB to Serial converter ( http://www.newegg.com/Product/Product.aspx?Item=N82E16812339013 ) at the PC with a serial cable ( http://www.radioshack.com/product/index.jsp?productId=3964614 ) connecting from the converter to the chamber, I can't find what type it is.
The driver I am using is the 2009 version located at http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=E3B19B3E9722659CE034080020E748...
I am using Labview 2010 and have updated the NI-VISA Software to 5.0.3
The Watview software that comes with the controller communicates just fine.
In MAX the settings match with the controller, MAX indicates that "The device is working properly"
Settings listed in MAX are:
Baud Rate: 19200
Data bits: 8
Parity: None
Stop Bits: 1
Flow Control: None
When I use the VISA test panel I am able to Write the Command *IDN?\n to the controller without error. When I attempt to Read from the controller I get error BFFF0015.
When I run the ESPEC Monitor VI it generates an error at WLF4 Initialize.vi, error code BFFF000E.
Once again thank you for helping with this. I look forward to figuring this out and getting it working!
Regards,
PChemist
01-12-2011 10:56 AM
Update: I checked the Serial cable with my multimeter and it seems to be a straight through cable.
01-12-2011 11:06 AM
Hi PChemist,
Have you tried communicating to the instrument through hyperterminal?
Thanks!
01-12-2011 12:48 PM
I am not familiar with Hyperterminal. I was searching around and found this from another company who uses these contollers from the same thing.
http://chamber.testequity.com/rs232.html
________
We receive many calls each week regarding RS-232 communication issues. There are several issues which must be addressed in order to communicate successfully with the chamber. With thousands of chambers in the field, we have never had a verified case of a bad serial interface in the controller. Below are several of the most common communication issues.
Are you
using the correct cable?
The DB-9 connector is wired to accommodate a null-modem cable. A null-modem
cable has pins 2 and 3 swapped on each end. You CANNOT use a straight
through cable.
Is the baud
rate set correctly?
All TestEquity chambers
shipped since mid-2003 have the baud rate set at 9600. Older chambers
have the baud rate set at 19200. The baud rate of the controller MUST
match the baud rate in your communications program. The baud rate is
changed in the controller's Go to Setup\Communications menu. You may
require a password to enter the Setup menu. If so, call TestEquity to
get the password.
Does your
software communicate using the Modbus RTU protocol?
To communicate with
the controller from a PC, you need to run software that uses the Modbus
RTU protocol. You CANNOT use Hyperterminal.
Modbus Registers
Each controller
function has a "register" number which can be read or written to (when
applicable). These registers are listed Chapter Seven of the Series
F4 User's Manual (pdf, 4M) .
Common Modbus Registers
__________
It appears that I can't use Hyperterminal for testing with the F4.
Since is says that I cannont use a straight through cable I wired up a quick cross over adapter ( http://digital.ni.com/public.nsf/websearch/1EE0DD8AF67922FA86256F720071DECF?opendocument&Submitted&&... ) and tried it. I am getting error codes for function in MAX now. Do you guys know if the F4 requires Handshaking? I didn't wire that into the adapter, just pins 2, 3 & 5.
01-12-2011 12:55 PM
Hi Dennis I was wondering if you could help me 🙂 I am trying to complete a traffic control system using labVIEW. My scenario is "
Each road junction has the following functionality.
It is a crossroads of 2 main roads with traffic lights at the 4 corners with the timing set in the Control Engineer’s office. The lamps follow the standard sequence of Red, Red & Amber, Green, Amber and back to Red. Lights on the 2 roads must not be Green together but can all be Red for safety. Each junction can operate in 3 different ways dependent on the time of day.
I can get 1 set to work but am struggling to get a timing device set up. Any comments or examples would be greatly appreciated.
Liz
01-12-2011 12:59 PM
Update: The software that comes with the F4, Watview, can't communicate with the null-modem in place. It has no communication problems with the straight through serial cable.
01-12-2011 01:07 PM - edited 01-12-2011 01:09 PM
Hi PChemist,
Looking at the F4 it seems like it communicates using the MODBUS protocol. Which would explain why you can't use *IDN? from VISA test panels.
Have a look at this Developer Zone article.
http://zone.ni.com/devzone/cda/tut/p/id/7675
Hope this helps!
01-12-2011 03:17 PM
Thank you for the Modbus info. The Vi's I am using are already using Modbus and can't communicate. Since I last posted I performed a loopback test using the Loopback.vi supplied by NI, it passed successfully. This makes me think I am missing a setting somewhere, unfortunately the error codes I am getting are to generic to be helpful. I have included the library I downloaded from NI (for the F4) for reference if anyone is interested.
I really need to get this working, any guidance is much appreciated!
Regards,
PChemist