FUJITSU MHD2032AT - Manual (Page 185)

Operations
6-6 C141-E050-02EN
6.1.4 Response to diagnostic command
When the master device receives an EXECUTE DEVICE DIAGNOSTIC
command and the slave device is present, the master device checks the PDIAG-
signal for up to 6 seconds to see if the slave device has completed the self-
diagnosis successfully.
The master device does not check the DASP- signal.
After the slave device receives the EXECUTE DEVICE DIAGNOSTIC
command, it shall report the result of the self-diagnostics to the master device as
described below:
PDIAG- signal: negated within 1 ms and asserted within 5 seconds
When the IDD is set to a slave device, the IDD asserts the DASP- signal when
negating the PDIAG- signal, and negates the DASP- signal when asserting the
PDIAG- signal.
Figure 6.4 Response to diagnostic command
If the slave device is preset, PDIAG- is checked for up to
6 seconds.