Self Test

[sondericker]

How can I tell how many self test types a certain piece of equipment supports? Is there a standard response, like a description length of zero, that I can count of receiving if I ask for a self test description for a self test that doesn't exist?

-john

[sblair]

John,

There is no direct way, however as you suggested you could look for a description length of 0. You should also look for a NACK coming back, most appropriate would be a NR_DATA_OUT_OF_RANGE when requesting a description for a Self Test beyond the range it supports.

[prwatE120]

You shoud not rely on responses to GET:SELF_TEST_DESCRIPTION to indicate which self tests are implemented, as there is no requirement to support this PID even though you might be supporting GET/SET SELF_TEST.

Indeed some of our small effects cards have some test functions but do not provide any descriptions.


I think the only way is trial and error until we agree on a revision

regards

Peter Willis

[sjackman]

Perhaps a E120_GET_COMMAND_RESPONSE E120_PERFORM_SELFTEST could return two bytes: the current test running and the number of tests available, as the personality PID does.

Cheers,
Shaun

[sjackman]

The protocol states that PERFORM_SELFTEST returns a flag: only 0 or 1. Much more useful is to return the number of the test currently running, or 0 for no test. I would absolutely recommend this change for a future revision of the protocol.

Cheers,
Shaun

[sjackman]

GET SELF_TEST_DESCRIPTION with a "Self Test #" parameter of 0 -- which is defined to be SELF_TEST_OFF -- could return the maximum number of self tests.

Or, as I mentioned before, GET PERFORM_SELFTEST could return two bytes with the maximum in the second byte, just as GET DMX_PERSONALITY does.

A third alternative has ocurred to me: GET PARAMETER_DESCRIPTION can be used to get the minimum and maximum valid values. I had thought of PARAMETER_DESCRIPTION as only being useful for manufacturer-specific PIDs, but it seems pretty useful in this case.

Cheers,
Shaun

[sblair]

Shaun,

Those are all good possibilities for us to add in the future. For the time being, I would suggest going by the NACK DATA_OUT_OF_RANGE response to indicate that you are beyond the range of supported Self Test parameters.