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MTDATA – Phase Diagram Software from the National Physical Laboratory |
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The MTDATA
command line
interface All modules within MTDATA
share a common user
interface, which is essentially command-driven with on-screen help.
User control operates at four levels of user awareness. The prompt tells the user
very briefly the current level. For example
at the top level the prompt asks what module
the user wishes to select. The users responses here are given in red
italics and are assumed to be terminated by
a carriage return. Entry of a question mark
gives a menu of the keywords and other user
options at any point. WHICH MODULE ? ? ACCESS
The
above menu appears on entry of a question mark and the prompt returns.
To leave MTDATA from the module level the user
enters exit.
Information about the current version of MTDATA can
be obtained by entry of version.
Help
is obtained for any one of these options by entry of the option name
preceded by a question mark. For example to learn about THERMOTAB WHICH
MODULE ? ?thermotab The
user interface will accept any unique abbreviation. Thus in the above
example WHICH
MODULE ? th is acceptable but WHICH MODULE ? t is not sufficient, as
the "t" could stand for THERMOTAB or TERNARY. The correct entry will
cause the program to move to the THERMOTAB module and to issue a prompt
at the COMMAND level: WHICH MODULE ? th On
entering a module, the menu of commands can be obtained by entry of a
question mark, for example, for THERMOTAB: THERMOTAB
OPTION ? ? AUTOBALANCE Again, this menu can be displayed by entry of a
question mark, and the current module is indicated by a change in the
prompt, in this case to: THERMOTAB OPTION ? An appropriate response would be any of the
keywords in the list or their unambiguous abbreviations. Some command keywords bring immediate response
without further entry apart from carriage return. For example: In THERMOTAB, entry of go
results in
tabulation and/or plotting of thermodynamic functions. Entry of status
yields the
value of such parameters as temperature and pressure, and indicates
which database(s) and substance(s) have been selected. In all modules return
moves the user
back from the command to the module level. Each of these keywords is typed in and followed
immediately by <CR>. The majority of command keywords, however, require
a series of parameters with their associated values followed by an
exclamation mark !
to complete
them. It is this set of modifiers which constitutes the third level of
the program. Most command keywords must be followed by a valid
series of parameters and values and be terminated by !.
What
constitutes a valid series depends upon the option selected. The stop
option is
always available; it is used to abort a command. The main purpose of this section is not to give
exhaustive examples for each option keyword - details for these can be
found in information about the appropriate module - but to illustrate
the two main styles available for entries by the user. Perhaps the easier of the two methods for beginners
or intermittent users, is to allow the program to act as a guide
through the entry. A typical conversation, using THERMOTAB as an
example, would be: THERMOTAB OPTION ? tabulate TABULATE allows the user to define the destination
of the output TABULATE OPTION ? ? TERMINAL Keyword options or prompts are always available TABULATE OPTION ? terminal TABULATE AT TERMINAL,
ENTER YES OR NO yes This
sequence causes the output to go to the terminal TABULATE
OPTION ? ! Please note that each command sequence must be
terminated by ! THERMOTAB OPTION ? A
briefer form of interaction is more appropriate for the user familiar
with THERMOTAB, its options and parameters. The above conversation
could be replaced by one line of the format: <option keyword> [<parameter> = <value>] ! where
[] indicates allowable repetition THERMOTAB
OPTION ? tabulate
terminal=no ! Indeed, the system is flexible enough to take
several options and parameters on one line, provided they are in the
correct sequence. An example is given below which will repay further
inspection, once the remainder of the handbook has been digested: THERMOTAB OPTION ? use sgsub =all ! define
equation 'H2<g>% + O2<g> =
H2O<g>' ! plot terminal=yes ! go The
concatenation character % (see [ENDCHR on page concerned with
Configuration Variables) at the end of the first line is occasionally
useful because it allows more than one line on the screen to be treated
as though it were only one line of input. It results in a ? character
being sent as a prompt for the rest of the user's entry. Just
as, at the module and command level, keywords may be shortened to an
unambiguous abbreviation, so at the parameter/value level, the
parameters, and if appropriate their values, may be abbreviated. Thus,
in THERMOTAB: autobalance mode=decimal
substance=4 ! can be
shortened to: auto mode=dec sub=4 !
or even to au
m d su 4 ! In
the information for each module, for the sake of clarity, abbreviations
are rarely used, but this should not be taken to imply that
abbreviation is not recommended. Each user develops his/her own
shorthand, but a convenient rule is to abbreviate to a monosyllable,
since these are nearly always unambiguous,
and at this level they still retain a recognizable relationship to the
full form. A
special mention should be made of keywords containing underscores.
Generally speaking, the part of the keyword on either side of an
underscore may be abbreviated, and in appropriate cases, deleted
altogether. Thus in MULTIPHASE: set lgt_pressure(1)=-6 !
may be
abbreviated to: set l_p(1)=-6 !
or even set
_p(1)=-6 ! In this case the
underscore itself cannot be dispensed with but only because LGT is not
unique.
The above is an example
of a subscripted keyword. The subscript is bracketed and always applies
to components, substances or phases. In some cases the subscripts can
include multiple values. Depending on the particular function the
subscripts may be numbers or character strings or in some cases either.
The on-line help
should be used to determine which. Where multiple values are possible
entry of * or all results in the operation being applied universally.
Examples are given below. classify absent phase(bcc)
s(all) normal s(1-7,16) ! In the above example
the BCC_A2 phase and all of the substances are removed and then some of
the substances are restored. Commas and hyphens are the only delimiters
allowed within the brackets. Note that bcc is an
acceptable abbreviation. set n 1 n(1) 0.3 ! In a two component
system the above command would set the total moles to 1 and that of the
first component to 0.3. The amount of the second component would be
calculated by difference. set n(CO2) 0.2 ! set n(CO2<gas>)
0.2 ! The above two examples
give quite different results. In the first 0.2 moles of C and 0.4 moles
of O are added to the overall system composition, in the second the
final amount of CO2 present in the gas phase at
equilibrium is 0.2 moles. set n( ) 1 2 0.2 ! If the system were
C-H-O, the above command would set the amounts of components C, H and O
to 1, 2 and 0.2 moles respectively. The user would be prompted if
insufficient values were entered. ordinate
component_distribution component(Fe) ! The above command would
change the graphics ordinate to the distribution of Fe between the
phases. A macro is a file containing exactly the same sort of commands, parameters and values as a user would enter from the terminal. The system editor could be used to make up a file like the following example in which the file is named step.mac.
In the above example, lines prefixed by a semicolon
are purely remarks; those prefixed by a colon are echoed to the screen
during macro operation. Macros are particularly useful when the effects
of varying the data are to be explored. Macros avoid the repeated
typing of commonly repeated conditions and in this particular
example the macro functions as a mini batch file, undertaking the
production of a series of graph files while the user gets on with other
tasks. This particular macro begins with a multiphase command and can
therefore be invoked from within MULTIPHASE by prefixing the name of
the macro with an apostrophe as follows: MULTIPHASE OPTION ? 'step.mac' There is a useful
overlap in the functions of macros and batch operation of MTDATA.
Advice on the generation and use of batch files can be found elsewhere
on the MTDATA web site. Macros may include user defined input points,
because parameters will be prompted for if not supplied on the original
command line in the macro file. "Silent" and "echoing" comments may be
inserted into macros. These facilities, when used together provide a
mechanism for customising the user interface. A disadvantage is that
user input must be completely accurate. The macro will not recover from
erroneous input unless [MACRO=CONTINUE has been entered as is the case
in all log files. In MTDATA it is possible to assign values to a range of settings that apply across the whole of MTDATA and affect a number of ways in which MTDATA appears or the accuracy of the calculations. These are called "Configuration Variables" and are assigned through use of "[" followed by the appropriate variable name. A list of the most important Configuration Variables can be obtained here. By default MTDATA
automatically produces a log of all user interaction and of data
sources used. The log opens when the user enters MTDATA
and closes on exit. Log files are generated in the directory from which
MTDATA is run. They are named consecutively in
the form mt123.log. Each
line of user input will appear twice in the file: once prefixed by a
colon to provide an echo to the screen, the other executive. The log file may be
used as a macro to repeat exactly what was done on a previous occasion
or it may
be edited to change the calculations or to prevent the macro exiting.
In this case it is recommended that the mt???.log file is copied to one
with the same root name but the extension .mac, so that the original
log file is preserved and the macro can be easily identified. For
purposes of total quality management all datafiles
(those with the extension .mpi) should be preserved with the relevant
.log files. |
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Updated 2 March 2010