how to read 1 more parameter using present program for temperature contoller

[kranthi1283]

hii

i am new to labview. i am developing VI of a temperature controller.what i basically need to do is to read present temperature as well as read set temperature and write set  temperature to the device.with progam i am having i am able to read present temperature only.so how can i modify the program so that i cab read 2 parameter ata a time and write to the device . i am using RS 232 cable for interfacing.so plz suggest me wt to do in detail.i am attaching my prog

thanking you

naveen

[Robert M]

What are your instruments commands to read the set temperature and write set temperature?  You can copy what you have already done to read the present temperature and replace the string with the command to read the set temperature.  A similar format will probably be used to write the set temperature, it just depends on your instrument's command set.

[BiomedEE]

The first things you need to answer are:

Are you trying to use modbus?

Does your temp controller use a CRC on all communications?

Typically what you want is done from register reads and writes all with CRC's on the reading and writing. One may need to know the registers to read and write to, and if your temp controller needs it you may need to set up a package of communication protocol along with what you want. The package may contain a device address, a function code, parameter address, register offset, how many bits/bytes you are reading and/or writing, along with the CRC.

If you are not modbus your job is easier - maybe only though. If you require a CRC they can be nasty or easy if example provided.