For the Assignment, see the SVN. You can also access it from the command line as follows:

svn export https://svn.eecs.yorku.ca/repos/4312/2015F/Public/Assign-Isolette

(you will need the SVN login/passwd)

Question: m_st is described as the status of the sensor and operator settings. When does the controller set it to invalid?

Answer: The prefix “m” in m_st means that m_st is a monitored variable and thus we cannot set it (or control it). It comes from the Plant (i.e. the environment). It signals invalid if any of the sensors have failed or if the operator console (another device in the Plant) has failed. Thus, this falls into the category of an E-description not an R-description.

The Controller (the SUD) can now use m_st to decide whether to sound an alarm or not (see REQ3).

(Rationale: In REMH, each sensor has its own failure channel. To keep the assignment manageable, have conglomerated all the failure channels into one variable, i.e. m_st)

Question: In the isolette-assign.pdf file, the Controlled Variables table lists a variable c_ms, described as “messages to display to nurse”. Reading the isolette-readme.pdf and the isolette spec in REMH does not result in a description of what this particular variable might contain. Please either provide clarification.

Answer: I'll let you think about the best way to do it, within the following customer constraints:

(1) declare an enumerated type MESSAGE or ERROR for c_ms with elements (i.e. a code) 8 characters or less like “low” or “high”, etc.

(2) Always display the most pressing error (if any) – not all the errors simultaneously.

Rationale: This reduces confusion on the part of the nurses.

You will need two tables:

(a) a table that maps the error code (e.g. “high”) to a more verbose and meaningful message.

(b) a function table that also expresses the order of display. In class we explained a specific table format for this kind of specification (this is the only case where we allow the keyword ELSE in a function table).