Test and Measurement Forum

Scaling Files

Scaling Files

Postby JamieDicks » Thu Jun 23, 2005 11:31 am

Hi All

I have an EL008 connected to an EL001 and then an EL037 in 4-20mA mode. Can you tell me where I can find information about 'Scaling Files' so I can set the equipment up to display temperature rather than current?

Kind Regards

Jamie

:?:
Jamie Dicks
Clinical Scientist
Medical Physics Department
Queens Medical Centre
Nottingham
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Postby Sarah » Fri Jun 24, 2005 9:50 am

Hi

Thank you for your post. The information is available in the signal conditioners help manual and is as follows:

The EnviroMon system only supports scaling for the EL016, EL036 and EL037 converters. You can create a user scale file, USER.PSC, that will not be overwritten during software upgrades.

You can copy an entry from one of the standard .PSC files to USER.PSC, then make changes as required. Remember to change the Sensor number to a value in the user range (1-99) so that it does not clash with the entry that you copied. You can edit .PSC files using the Windows Notepad program.
Pico software carries out scaling using a lookup table- a list of pairs of values, where each pair is made up of a raw value (in millivolts, unless the signal conditioner measures something different) and a scaled value in the appropriate parameter units.

For a sensor with a linear response, exactly two pairs (or points) are required- ideally, the top and bottom of the measured range. For a sensor with a non-linear response, more points will be required. Note that a large number of points may cause memory shortage problems in the EnviroMon.
Below is an example of a scaling file which you can copy into your own user.psc and alter as desired. There explainations of each entry below.


For each scale that you require, there is a section like this:
[Scale1]
Name=Honeywell 26PC 0-5psi
Conditioner=15
Sensor=121
Units=psi
OutOfRange=2
Places=3
Method=0
NoOfPoints=2
Raw1=0
Scaled1=0
Raw2=100
Scaled2=5


Name=Honeywell 26PC 0-1psi

This is the name of the scaling method. The same scaling method could be used for multiple sensors (in this case, for example, the pressure from a number of different sensors of this type.

Conditioner=15
This specifies the type of conditioner that the sensor will work with. If this sensor does not require a signal conditioner, set the conditioner type to zero.
For the the 0-2.5V channel on the EL037 V/A converter, you need to set Conditioner=371, the 0-10V channel 372 and the 4-20mA channel 373.

Sensor=121
This is a unique reference for this scaling method. If you add your own sensors, please use sensor numbers in the range 1 to 99.


Units=psi

The units appear next to the parameter value on graphs, reports etc


Places=3

This is the number of decimal places. The options are 0, 1, 2 and 3. With places=1. The value 15 would be displayed as 15.0. With places=2, the same number would appear as 15.00.


Method=0

This specifies the scaling method. At the moment, 0 (table lookup) is the only method.


Onoff=No

This parameter is currently used only for EnviroMon.
For numeric parameters, Onoff should be No. For parameters that can have only two values (on or off), this should be set to Yes, and the scaling should be set so that for places = 1, on = 100 and off = 0. The logger will then display On or Off for the parameter, and reports will show the percentage of time that the parameter was On.


OutOfRange= 0

This specifies what to do if the raw value is outside the range of the table lookup. The options are:
0 - treat as a sensor fail
1 - clip the value to the minimum or maximum table value
2 - extrapolate the value using the nearest two table entries.


NoOfPoints=2

This is the number of table lookup points.


Raw1=0
Raw2= 16.7

These are the raw values for the first and second points. The raw value is normally in millivolts, however the CM007 (4-20mA) conditioner, it is in mA.

Scaled1=0
Scaled2=1

These are the scaled values for the first and second points (Raw1 corresponds to Scaled1, etc). It is in the units specified by the Units parameter.

Hope this helps

Best Regards
Sarah
 

.PSC Files

Postby JamieDicks » Tue Jun 28, 2005 2:16 pm

Hi

Thanks for the recent post. Now I have another question about .PSC files.

We are using a EL037, together with an EL001 and some suitable thermocouples and amplifiers. The thermocouples will be placed in a dewer containing liquid nitrogen so I need to set the scaling to reflect the temperatures between the boiling point of liquid nitrogen (-195 degrees C)and room temperature (say 25 degrees C). Does this mean I need to set the Raw1 value to the minimum millamps, somewhere around 4mA, that corresponds to the temperatue of liquid nitrogen and Raw2 value to 20mA or so that corresponds to the maximum value, room temperature?

Do I then set the Scaled1 value to say -195 and Scaled2 value to say 25?

Would this work?

Kind regards

Jamie

:lol:
Jamie Dicks
Clinical Scientist
Medical Physics Department
Queens Medical Centre
Nottingham
JamieDicks
Active User
Active User
 
Posts: 8
Joined: Wed Mar 02, 2005 2:49 pm

Postby Sarah » Wed Jun 29, 2005 9:25 am

Hi

Thank you for your post.

You can have as many raw and scaled pairs as you want - if the sensor has a non-linear response then you will want to have several pairs there to give more accurate readings. If it has a linear response then you only need two values - the maximum and the minimum. This is because the software will interpolate the results from the values you have given it.

The values you describe will be fine if it has a linear response, if it does not then you will need more values in between.

Hope this helps

Best Regards
Sarah
 


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