Internet PLC Forum

I've run into a bit of a problem with the NANO-10 Analog Inputs.  I have damaged the inputs on 2 of my NANO-10 boards.

I have attatched a schematic of a possible input protection circuit.  I am looking for feed back.

The sensors that I am working with output a 4 to 20 mA current source.  The 250 ohm resistor converts this to voltage between 0 and a bit less than 5 VDC.  I am aware of the 2K input impedance of the analog inputs.

The 5.1V Zener diode is an attempt to limit the voltage that the analog inputs "see". The Zener is supposed to clamp the voltage to about 5.1 VDC max and if the input voltage goes below ground the Zener will behave like a normal diode and clamp the low voltage to about -0.7 VDC.

The 120 Ohm resistor just limits the current that flows in the circuit and does not affect the accuracy of the measurement (the sensor outputs current and not voltage). The 0.01 uF capacitor is an attempt to bypass transient events to ground.

Gary Diuckinson

A long time back I worked with the pre-production Wx100 product using any of a number of versions i-TRiLOGI that were test builds.

I got an email from a Wx100 user and he was having problems with compiling a Wx100 program that I wrote.

The affected file is named "Wx100 Simple Menu V1_12.PC7.

The problem is that this demo code was written with an early version of i-TRiLOGI when the "Comment" field was added to the #define mechanism.  The current tool set V7.5 Build 14 uses a different field separator in the .PC7 file than was used by the early version that I wrote the code with...

The early version used commas as field separators in the PC7 file. Sort of like this:  #,Defined Name,Value,Comment
The current tool set uses commas and an ASCII <RS> (record separator). Looks like this: #,Defined Name,Value<RS>Comment

The problem is that my "old" code when compiled with current tools doesn't recognize the "," before the Comment field so the Value field ends up with the correct "Value" a comma and then the Comment text.  The Comment field is always empty.

I was able to fix the problem for the user, by exporting the #Define Table to a text file and replacing the first "," character by an ASCII TAB character and then importing the edited #Define table back into the PC7 program.  The edited #define table now works perfectly and if I peek into the PC7 file I see the <RS> character in the correct spot.

I have attached the corrected .PC7 file.  It is now named "Wx100 Simple Menu V1_13.PC7.  The only changes from the V1_12 file is the corrected #define and I added a comment for the V1.13 version to give a hint as to why it was changed.

I think that the V1.12 version may appear in in the Wx_Specifics directory and in a Zipped file named "Wx100 Simple Menu.  Is this something that you can fix in a future release?

Best regards,

Gary Dickinson

The Print Dialog box gets overwritten with parts of the displayed .pc7 file after pressing on the "Print" button.

See attachment

Gary D

I am working on a PLC project that needed to use Thermistors for temperature measurements.  This is not a new topic, but for my current application I decided to see if I could do this without the traditional lookup table and linear interpolation algorithms.

My application did not only required accuracy over a range or 30 or 40 degrees C. 

I was able to get the math for converting ADC counts to temperature to a single equation for my application:
 
      y# = x * 2.1095E-2 - 3.3485E+1         

No lookup tables.

So I am sharing how I got to this sort of solution. Perhaps, it would be useful to others.

I have attached the documentation to this message. I will post the Excel spreadsheet on the next message in this thread.

Gary Dickinson

I am presenting the code that I have been using for the last 5 years as an alternative to the TBASIC ReadModbus, ReadMB2, WriteModbus and WriteMB2.

This code is supports all possible Modbus function codes.

This code is non-blocking. The PLC does not lock up waiting for a response from the slave device.

This code is an example of a user written communication protocol

This code allows you to see both the Modbus response packet and every byte received from the Modbus slave.  This allows you tremendous debug capability that is not available with the TBASIC Modbus support.

I will post the PLC code and the documentation in pieces to keep them under 200KB

Regards

Gary Dickinson

Gentlemen,

I am quite confused about the goto statement. I have never used one as it is considered by many to be "unsophisticated".  But I have been playing with them in an attempt to write a CF that consumes a lot of CPU time without the use of for/next, while/endwhile, delay or SetLCD statements as all of these resets the WDT mechanism.

So I set out to write a non-sense program that used nested for/next loops and a lot of string functions. I picked on the string functions because they are slow.

I wrote the following nonsense code and cannot get it to compile:

' for_next
'
' This code is an eumulation of a for/next loop using goto statements
'
'
/*
   for j = 1 to 3
      b = b + b
   next
*/


j = 1         ' loop counter initialization
@200
if j > 3      ' range check
   goto @220
else
   ' loop body
   '
   b = b + b
@210   ' continue entry point
   j = j + 1   ' counter + step value
   goto @200
endif
@220         ' loop exit
[/color]

The compiler exits with the following error message:

Error:Undefined GOTO destination: @: "-36"

and the first 3 characters of the last line of the program are highlighted in yellow:

@220         ' loop exit

Any idea what this error message means?

Any idea what I have done to offend the compiler?

Best regards,

Gary D*ckinson

I have attached the PLC program StepperTest V2_01.PC6 to this post.

This is a test program that I wrote about 3 years ago to test a stepper motor-controlled valve.  This is a simplified version of that test code.  

If you are thinking about use the PLC for stepper control, this is an excellent starting point as all of the code can be used and extended for your purposes.

Best regards,

Gary D*ckinson

I just tried to see if a new update to the i=TrRiLOGI software was available by clicking

Help->TRiLOGI Update  (from i-TRiLOGI V 7.12 Build 04)

This opened my default web browser  with this URL: http://www.triplc.com/TRiLOGI/Help/upgrade.htm

Unfortunately this URL cannot be found and my browser returned a 404 error.

I assume that things are in flux and I will check back later.

Best Regards,

Gary D*ckinson