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Chapter 6 Advanced Topics 85
TTL Control
Fully supported by WinView/WinSpec Version 2.5 when the communication protocol
is TAXI (PCI), this feature is not supported when the protocol is USB 2.0.
Introduction
This connector provides 8 TTL lines in, 8 TTL lines out and an input control line.
Figure 41
illustrates the connector and Table 13 lists the signal/pin assignments.
Princeton Instruments WinView/32 software packages incorporate WinX32 Autom
ation,
a programming language that can be used to automate performing a variety of data
acquisition and data processing functions, including use of the TTL IN/OUT functions.
WinX32 Automation can be implemented in programs written in Vision Basic or Visual
C++. See the WinX32 documentation for more detailed information.
TTL In
The user controls the 8 TTL Input lines, setting them high (+5 V; TTL 1) or low (0 V;
TTL 0). When the lines are read, the combination of highs and lows read defines a
decimal number which the computer can use to make a decision and initiate actions as
specified in the user’s program. If a TTL IN line is low, its numeric value is 0. If a TTL
IN line is high, its numeric value is as follows.
TTL IN Value TTL IN Value
1 1 5 16
2 2 6 32
3 4 7 64
4 8 8 128
This coding allows any
decimal value from 0 to 255 to be defined. Thus, as many as 256
different sets of conditions can be specified, at the user’s discretion, using the TTL IN
lines. Any unused lines will default to TTL high (+5 V). For example, to define the
number three, the user would simply set the lines TTL IN 1 and TTL IN 2 both high
(+5 V). It would be necessary to apply TTL low to the remaining six lines because they
would otherwise default to TTL high as well.
TTL IN Value TTL IN Value
1 High (1) 5 Low (0)
2 High (2) 6 Low (0)
3 Low (0) 7 Low (0)
4 Low (0) 8 Low (0)