Measurement Computing Digital232 - Manual (Page 18)

Section 2 Getting Started
2.10
2.3.3 Control Lines
Five control lines enable handshaking of digital I/O data transfer to the
Digital232. They are automatically activated with the corresponding I/O activity
and can also be independently activated with the Handshake (Hn) command.
2.3.3.1 Clear (Pin 41)
The Clear output is pulse for approximately 50 microseconds at power-on,
or upon receipt of the RESET (@) command. The Clear line is normally
active high. The Invert command (I8) will program it active low. The
Handshake command (H0) can pulse the Clear line, independent of any I/O
operations.
TIMING DIAGRAM FOR CLEAR OUTPUT
2.3.3.2 Data Strobe (Pin 42)
The Data Strobe output is pulse for approximately 50 microseconds after
new data is output on the I/O port. The Data Strobe line is normally active
high but may be programmed active low by the Invert command (I4). The
Handshake command (H1) can pulse the Data Strobe line, independent of an
I/O operations.