I downloaded the Modbus Library and was able to get the program working. I then went back and checked the Modbus functions in LabVIEW 2014 once I knew what I was doing and they worked also. The program had four errors that were solved by a couple of people. Three errors were solved by smithd. The default settings of the CAL 3300 is address 0, baud 9600, parity none, and 1 stop bit. Smithd pointed out that 0 cannot work as a calling ID and the CAL 3300 doesn’t follow Modbus specifications with parity of none. I needed to change the ID to 1 and use even parity. He was also correct that I needed to set a property node to RS485/wire2-Auto. Sundown thankfully provided his code which allowed me to see how to write a new set point to the CAL 3300. The last error was with my wiring. I kept searching for cabling configurations because I thought there had to be an error there since nothing was working with all the help I was getting. I then came across this article
http://www.windmill.co.uk/rs485.html
Which made since to me. That prompted a search under the instrument control forum that resulted in the follow discussion solved by Frabto.
http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/RS485-half-duplex-2-wire/td-p/1668918
My new wiring is:
TX/RX+ To pin 4 and 8
TX/RX- To pin 5 and 9
Gnd To pin 1
Thanks to all for the help. Sundown can you mark this topic as solved.
