Allen-Bradley A-B QUALITY DL20 Series User Manual page 86

Chapter 7
The Parallel Port
Reducing Host
Output Requirements
11A 11B
D9 D8
11A 11B
D9 D8
7–14
If messages don't contain variable data, the number of outputs can be
reduced. Since no variable data is transferred, both strobe lines are always
zero, or always one. In addition, some data lines (D0 - D9) could be
eliminated depending on the highest message number used.
Figure 7.3 illustrates this method.
Figure 7.3
11 Ouput Configuration
12 13 14 15
D7 D6 D5 D4
PC Outputs (11)
You can further reduce the output requirements by tying the strobe lines high
as shown in Figure 7.4
Figure 7.4
10 Output Configuration
12 13 14 15
D7 D6 D5 D4
PC Outputs (10)
16 17 18 19
D3 D2 D1 D0
16 17 18 19
D3 D2 D1 D0
Terminal
21 20 23
Number
Terminal Block
MS0 MS1 GND
Designation
-
+
21 20 23
MS0 MS1 GND
-
+
Tie Together
For HIGH
TRUE Logic
Only
Power Supply
5-30 VDC
(Observe DC
Polarity)
Terminal
Number
Terminal Block
Designation
Power Supply
5-30 VDC
(Observe DC
Polarity)