FlexLogix Analog Scaling Help please!

As a Contrologix programmer I have always Right clicked on the Analog modules in the I/O Tree and scaled them 0-100 and then did programming math to scale the signal depending on Min Max values of the Analog devices.

I have a small project this weekend installing a Flexlogix that has one FlexIO Analog Input and one Analog output. There is no way to scale the module from the Module properties.

Can someone help me with the Code or Bits that need to be set to get this done? Right now as an example I have to [MOV] about 4000 to the analog out to get 20 Millamp.

NOTE: The analog cards are configured for 4-20 Millamps and wired correctly.

Thanks in advance
Bob

You are going to need the manual for the Flex I/O module, these modules usually support many scaling schemes, and only you know the requirements of your process.

Only controllogix modules have internal capacity to do scaling.
Flex modules never had this.
You will have to do it in the program
As you did not specify what flex module you have I assume it is 1794-OE4
Get this manual:
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1794-um002_-en-p.pdf

Page C-2 gives you scaling data and page C-3 shows how to do scaling

Now I am confused, I know how to do the programming with a PLC2, PLC3 or PLC5 but this is Flexlogix and I am using Contrologix software. The Module is an 1794-OE4 as discribed above and the manual does not give programming examples for that software family.

Could someone point me in the right direction. Do I move values into the Controller tag configuration or what? Do I scale the Raw Data with Math if so what is the Raw data 4-20Mamp = 0 to 4096? Or am I all wet here?

Thanks Bob Low

You will have to do scaling using CPT instruction

Result of CPT will be written to the Local:<slot>:O.ChxData tag

If you configured module for 4-20, then you will write 0 for 4 mA and 30840(=7878hex) for 20mA.

Scaling:
Assuming
RawMax expecting at 20mA
RawMin expecting at 4mA

Formula in your case will be: 30840*(RawData-RawMin)/(RawMax-RawMin)

Thank you for the clear answer to my question. After reading this I remember doing this with RSLogix 500 the same way.

Does anyone off hand know what the raw data coming into the PLC would be for the 1794-IE8 I think it is, The 4-20 Millamp Analog input module?

Thanks
Bob

1794-IE8 configured for 4-20mA would have the following raw values:

4 ma = 0
20mA = 30840 decimal (7878 Hex)