Watlow Ez zone Modbus control with Labview

[paulangl]

Hello !

I'm trying to control an Ez Zone Watlow temperature controller through modbus via Labview. I've downloaded the basic VIs provided by Watlow to do this, and had them converted from v 8.6 to 8.0 (I'm running on Labview 8.2). The Ez Zone is connected to the computer (Win XP SP3) with a serial RS485 crossed cable on the PC's serial port COM1.

When I run read.vi (attached below) in Labview, and try to read a random parameter, it returns a empty string and this error :

Error 1 occurred at an unidentified location

Possible reason(s):

LabVIEW: An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @.
=========================
NI-488: Command requires GPIB Controller to be Controller-In-Charge.

I don't really understand how this VI works, because althought it calls a .dll file, I don't see how the connection to the instrument is made.

The serial port is configured as follows :

Bits/s : 9600

Data = 8 bits

Parity : none

Stop : 1

Flow control : none

... which is the default communication configuration on the instrument.

Thanks for your help,

Paul

[JohnHWhite]

Hi

The only problem I remember having with this controller was that the RS485 connection is half duplex NOT full duplex. I only used this to set the IP address using their supplied software as the controller had a Ethernet\ModBus adaptor and I used that for all the LabVIEW programming.

John

ps Are you running the initialize VI first?

[onlyjus]

I am having the same problem. Did you ever fix this?

http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/bd-p/140