

				   PRT Calc
				  ~~~~~~~~~~
                  Platinum Resistance Thermometer Calculator                 
                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                

     I. Introduction.
    II. Main menu.
   III. Manual calculation.
    IV. Automatic calculation.
     V. Valid keyboard inputs.
    VI. Small print.


I                                  PRT Calc
				  ~~~~~~~~~~
   PRT Calc  is  intended  as  an aid for anyone who uses platinum resistance
thermometers. It will calculate the resistance of a PRT  at  any  temperature
within  the  specified  range  or  will  calculate  the  temperature  if  the
resistance is known. PRT Calc can, therefore, be used by  people  calibrating
or designing platinum resistance thermometers based on BS 1904, or people who
wish to use PRT sensors directly into a DVM or bridge without any intervening
electronics.
   The formulae used by PRT Calc  were  derived  from  the  British  Standard
BS 1904 : 1984, for which full credit is acknowledged.  The  formulae  should 
give no errors greater than the least significant digit  in  the  BS  tables, 
hence ensuring that any results obtained by this program can be considered to 
be correct for all practical purposes. (If anyone discovers any errors PLEASE 
let me know).


II                                MAIN MENU                                  
                                 ~~~~~~~~~~~                                 
   The  main  menu  in  PRT Calc is used, both to change the various options,
such as temperature scale, and to initiate the different modes of operation.
   Menu items are selected by using the vertical curser controls to highlight
the required item, or by pressing the appropriate  number  or  function  key. 
Once an option item has  been  selected,  the  option  can  be  activated  by 
pressing RETURN or changed by using the horizontal curser keys,  or  in  some 
cases by pressing a letter key. Brief instructions are given at the bottom of 
the screen for each item. Details of each item are as follows.
     1. Help
This item invokes the Help mode and,  basically,  displays  or  prints  these 
pages.
     2. Exit to DOS
Exits from PRT Calc to DOS or whatever shell is in use.
     3. Manual calculation
This starts the  normal  mode  of  operation  in  which  the  user  inputs  a 
temperature or resistance and PRT Calc calculates the other (depending on the
setting of the direction option). 
     4. Automatic calculation
This mode is more useful if the  user  wishes  to  create  a  mini  table  of 
results. (The original BS tables are obviously better  if  more  than  a  few 
values are required.) PRT Calc prompts for a starting value, an end value and
a step size. It then performs the required calculations automatically. It  is 
advisable to enable the printer option before using this mode.
     5. Change direction
This is one of the option  items,  with  just  two  options;  temperature  to 
resistance or vice verse. The default is temp > res. in which case  the  user 
inputs a temperature and  PRT Calc  calculates  the  corresponding resistance
Either of the horizontal curser keys, or the RETURN key, just toggle  between 
the two options.
     6. Printer output
This is another  two  option  item;  enabled  or  disabled.  The  default  is 
disabled, in which case the results are displayed on the screen only. If this 
option is enabled then results are also output to a printer (assuming one  is 
connected of course).
     7. Select temperature scale
This item  has  four  options;  C,F,K,R;  (Celsius,  Fahrenheit,  Kelvin  and 
Reaumer). The default is C. The horizontal curser  keys  scroll  through  the 
options, or the choice can be  made  directly  by  pressing  the  appropriate 
letter key. 
     8. Nominal resistance
This item enables the user to enter the nominal resistance of the  PRT  (i.e. 
at 0 C). The default for this value is  100 ,  which  is  the  normal  Pt100 
standard. There are few exceptions, such as some high temperature probes. 


III                           MANUAL CALCULATION                             
                             ~~~~~~~~~~~~~~~~~~~~                            
   To start manual calculation, highlight item 3 in the main menu  and  press 
RETURN, after changing any of the options if required. Manual calculation  is 
the normal mode of operation for PRT Calc. It accepts any valid input entered
via the keyboard and immediately displays the result. 
   Firstly it displays a header showing  the  current  settings  of  all  the 
options and then prompts you for an input. If the input is valid (see section 
headed Valid Keyboard Inputs) it then displays both the input and the  result 
in two columns. (The reason it redisplays the input is that it does so  in  a 
consistent, readable format, acting as  a  visual  check  on  the  input  and 
tidying up the printout if enabled). If the printer option has  been  enabled 
then the header and both columns are also printed. If the  input  is  invalid 
then a warning message is displayed (and printed). If the input is only  just 
outside the valid range then a result is given along with a warning that  the 
result is only approximate. 
   When you have finished, or to change any of the options, press RETURN with 
no input. This returns you to the main menu. BUT REMEMBER,  any  results  not 
printed will be lost. Also, any results which  scroll  off  the  top  of  the 
screen will be lost, so it is advisable to enable the printer if more than  a 
screen full of results are expected. The  contents  of  the  screen  can,  of 
course, be printed at any time by pressing the Prt Sc key. 


IV                          AUTOMATIC CALCULATION                            
                           ~~~~~~~~~~~~~~~~~~~~~~~                           
   This mode works in a  similar  manner  to  the  manual  mode  but PRT Calc
supplies the inputs. To start this mode, highlight item 4 and  press  RETURN. 
PRT Calc will display (and print if enabled) the header and  then prompt  you
for three pieces of information: start, end and interval. For example, If you 
want the results for all values from 50 to 100 in steps of 0.5 then enter  50 
as the start value,  100  as  the  end  and  0.5  as  the  interval. PRT Calc
interprets your input but does not check for out  of  range  values  at  this 
stage (see Valid Keyboard Inputs). PRT Calc then  asks  you  to confirm  your
input and, if OK, it performs all the calculations automatically,  displaying 
(and printing) the results in two columns. It is at this stage  that  out  of 
range warnings are issued in the same manner as the manual mode. 
   Because of it's automatic nature, and the fact that any  results  scrolled 
off the screen will be lost, it is advisable to  always  enable  the  printer 
option before using this mode; assuming, of course, that you have  a  printer 
connected). 


V                           VALID KEYBOARD INPUTS                            
                           ~~~~~~~~~~~~~~~~~~~~~~~                           
   PRT  Calc  is  fairly  versatile  in  what  inputs it will accept, but not
limitless. You can use normal numbers (E.G. 0.0015  or  2300),  you  can  use
scientific  notation  (E.G.  1.5e-3 or 2.3e3), or you can use a suffix letter
(E.G. 1.5m or 2.3k). When using a suffix PRT Calc will accept f,p,n,u,m,k,M,G
or T. It will even accept the Greek letter  (mu) if you want to be pedantic!
Anything after the first letter is ignored so 2.3k is sufficient for 2.3  k.
The  suffix  must NOT be placed in the middle of the number, I.E.- 2k3 is NOT
valid and will be interpreted as 2k. Commas must NOT be included. 2,300  will
be interpreted as 2.
   Temperature inputs must be in the selected temperature  scale.  To  change
the scale use item 7 in  the  main  menu.  All  inputs  must  be  within  the 
specified range, although inputs just outside the limits will be accepted and 
a warning displayed. The valid range is displayed in the header. 


VI                               SMALL PRINT                                 
                                ~~~~~~~~~~~~~                                
   PRT Calc is intended to be User Supported, which means you are free to use
it, copy it and pass it on to anyone on a trial basis. However, if  you  find 
it useful then a financial contribution to the  author  would  be  in  order. 
Companies should send 50 but if you  are  a  private  individual  just  send 
whatever you think the program is worth to you. (Contributors will receive  a 
copy of the latest version of this program and maybe others I happen to  have 
lying around at  the  time!)  There  is  no  printed  manual  available  (you 
shouldn't need one!) and there is no official after sale support. However, if 
you are able to get in touch with me then I will give any assistance I can.
   Suggestions and corrections will be accepted just as  enthusiastically  as 
money (well almost!).
                                           Roly Williams
                                       22 Morrison Drive
                                              Lennoxtown
                                             Strathclyde
                                                 G65 7BA

                                       Phone; 0360-31157

