National Instruments AT-DIO-32F, User Manual

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Chapter 3 Theory of Operation
© National Instruments Corporation 3-11 AT-DIO-32F User Manual
RTSI Bus Interface
The AT-DIO-32F is interfaced to the National Instrument RTSI bus. The RTSI bus has seven
trigger lines and a system clock line. All National Instruments AT Series boards that have RTSI
bus connectors can be wired together inside the PC to share these signals.
The RTSI bus RTSICLK line can be used to send a 10-MHz signal across the RTSI bus, or to
receive another clock signal from another AT board connected to the RTSI bus. MYCLK is the
system clock used by the AT-DIO-32F.
The RTSI switch is a National Instruments custom-integrated circuit that acts as a seven by seven
crossbar switch. Pins B<6..0> are connected to the seven RTSI bus trigger lines. Pins A<6..0>
are connected to seven signals on the board. The RTSI switch can drive any of the signals at pins
A<6..0> onto any one or more of the seven RTSI bus trigger lines and drive any of the seven
trigger line signals onto any one or more of the pins A<6..0>. With this capability, any AT
Series board sharing the RTSI bus has a completely flexible signal interconnection scheme. The
RTSI switch is programmed via its select and data inputs.
On the AT-DIO-32F board, seven signals are connected to pins A<6..0> of the RTSI switch:
REQ1, REQ2, ACK1, ACK2, IN1, RWGRP1*, and RWGRP2*. These signals can be controlled
over the RTSI bus or externally across the I/O connector. The RTSI bus connections send timing
signals to other AT boards connected to the RTSI bus.