Chapter 7: I/O Wiring
59
External 5V
Supply
DSPpro
Amplifier
DSPpro
Amplifier
Amplifier Enable
Enable
Amplifier Enable
Enable
1Kohm
1Kohm
High Enable Input Amplifier
Low Enable Input Amplifier
Figure 7-7. Amplifier Enable Wiring
7.6 Opto-isolation
On the DSPpro-VME, dedicated and user I/O headers conform to Opto-22/Grayhill/Gordos
standard pin arrangement, and may be connected directly. Some Opto-22 racks do not use the
+5V logic power on pin 49 of the I/O connector. +5 volts must be provided from an external
source. Grayhill racks can be configured to take the logic power from pin 49 so that no external
source is necessary.
When power is first applied to the DSPpro boards, the User I/O signals come up in a high-
impedance state and the
amp_enable
line in the Dedicated outputs comes up low. Most opto-
isolation modules invert the I/O signals, which means that I/O signals may come up high. The
active level of the Dedicated I/O signals can be configured in the SETUP program and the boot
configurations of the User I/O signals can be set with the function libraries. Refer to the MEI
DSP-Series Motion Controller C Programming Manual
for detailed information.
DSPpro-Serial controllers have internal opto-isolation so no external I/O isolation is required.
7.7 Analog input wiring
7.7.1 DSPpro-VME
Analog inputs for the DSPpro-VME are connected to the 20 pin connector P8. Pins 2 and 20
(Analog GND) are connected to the logic ground of the A/D chip and to a separate ground plane
beneath the A/D chip. The logic ground of the A/D chip is also connected to the bus ground
(with all of the other GND signals). When connecting analog inputs it is often better to use the
separated analog grounds to improve noise immunity.
There are 8 channels, each with 12-bit resolution. Each channel can be configured as either
Unipolar (0 to 5V) or Bipolar (-2.5V to +2.5V). Since there is no buffer between the P8
connector and the A/D chip, the input voltages must not 5V or fall below -2.5V.
7.7.2 DSPpro-Serial
Analog inputs for the DSPpro-Serial are connected to the 50-pin connector P5 marked User I/O.
The MEI accessory STC-D50 can be used to simplify wiring. The STC-D50 includes screw-
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