Owner's manual

Chapter 4: PowerDAQ Software
42
PowerDAQ Software
PowerDAQ DIO board terminology
All DIO boards are visible to the external world as a set of 16-bit bi-
directional registers called ports. Valid port numbers are 0 through 3
for the 64 channel boards (lines 0..15, 16..31, 32..47 and 48..63
respectively) and 0 through 7 for the 128 channel board (additional
four registers represents lines 64..79, 80..95, 96..111 and 112..127
respectively)
Clock relative to the DIO subsystem is either input clock for the input
timed operations or output clock for the output operations. Only one
port-register updated/read per one clock at the time. Clock may be
either external or internal for both input and output. External clock, if
used, must be connected via 100-200 Ohm resistors to the TMR1
terminal for the input operations and TMR2 terminal for the output
operations and expected to be a TTL pulses with minimum of 32nS of
duty cycle. When internal clock is used TMR1 and TMR2 is a
corresponding clock output and may be used for multiple board
synchronization purposes.
ESSI clock is a different type of clock, which represents the speed of
bit input/output stream operation and configured via ESSI registers.
ESSI clock is derived from the Motorola DSP based frequency, which is
a 66MHz and does not depend on TMR1/TMR2 programmed
frequency.
External latch is a dedicated input terminal, which may be used to
latch input data externally. It may be combined with external clock for
the effective operation. There is only one external latch terminal per
every 64-channles.
Propagate signal is a dedicated output which pulses every time when
selected ports are updated from the host (or DSP during the streaming
operation). It may be used for the handshaking purposes. This output is
a software-configurable. There is only one propagate terminal per every
64-channles, but it may be configured to show update of any
combination of the four available ports for every 64-channel connector.