PMDX-132 User’s Manual
PCB Revision: PCB-466A
Document Revision: 1.0
Serial Numbers: 23410 and above
PMDX-132_Manual_10.doc
©2008 Practical Micro Design, Inc.
Page 6 of 24
17 April 2008
All Rights Reserved
logic high into pin 11 on the PC’s parallel port. Any number of “normally closed” switches may be
connected in series to a single input terminal on the PMDX-132.
Figure 2 – Example Switch and Optical Interruptor Configurations
Normally Open Switches
The center drawing in Figure 2 shows an example of “normally open” mechanical switches. The switches
are wired in parallel so that the “normal” case is +5V (logic high) going into pin 11 of the PC’s parallel
port (due to the pull-up resistor on the PMDX-132). When one or more of the switches close, a logic
low appears on pin 11 on the PC’s parallel port. Any number of “normally open” switches may be
paralleled onto a single input terminal on the PMDX-132.
Optical Interrupter
The right-hand drawing in Figure 2 shows an example of an optical interrupter. This example uses the
“+5V Aux Out” from the PMDX-132 to power the sensor. The output signal is connected as an “open
collector” output between the PMDX-132 input pin and ground. When light from the LED strikes the
sensor, the sensor conducts giving a logic low on pin 11 of the PC’s parallel port. When the LED is
“interrupted”, the transistor stops conducting and the PMDX-132’s pull-up resistor gives a logic high on
pin 11. The same basic operation applies to the “reflective” version of sensor, i.e. when the light from the
LED reflects and strikes the sensor, the sensor outputs a logic “low”.
2.4
Example Configuration with Daisy-Chained PMDX-122
The PMDX-132 can be connected to a PMDX-122 in a daisy-chain configuration. This allows the
PMDX-132’s charge pump, E-Stop and Fault circuitry to enable and disable the PMDX-122’s signals. This
configuration also allows the PMDX-122’s E-Stop input to be used as a general-purpose input.
Figure 3 shows a typical daisy-chain configuration. This requires two parallel ports in the PC: one for the
PMDX-132 and a second one for the PMDX-122. The PMDX-132 provides power to the PMDX-122 via
the unregulated “fan power” output on connector J5. The PMDX-122 is shown connected to two optical
encoders, with the data bus direction set to “input to PC”. This is just one example of how the daisy-
chained PMDX-122 can be used. Other uses include having the data bus drive Opto-22 relays. Make sure
to set the PMDX-122’s jumpers according to your configuration.
J8
GND
pin11
+5V
AUX
pin12
pin13
pin15
Three "normally closed"
switches in series.
J8
GND
pin11
+5V
AUX
pin12
pin13
pin15
Three "normally open"
switches in parallel.
J8
GND
pin11
+5V
AUX
pin12
pin13
pin15
Optical Interrupter
(slotted or reflective)
