The angle encoders have to be connected directly to the core module
of the sat-nms ACU2-ODU, which is called
sat-nms ACU2-ODM. Inside, the
sat-nms ACU2-ODM consists of a main board and
two or three interface boards with the circuitry for the position
sensors. These boards are different for each type of position
sensor.
It is essential, that the shield of the encoder cable is connected to
ground with low impedance at the cabinet, but not at
antenna side (isolate the shield well to ensure that shield is not
connected to antenna ground!). Also take care that the unshielded part
of the cable is as short as possible. To ensure proper ground connection
in the cabinet, there are two possibilities:
connect the shield to the PE terminals right below
sat-nms ACU2-ODM. Take care, that the shield
cable is as short as possible. You can see this on the following
picture.
there are three brackets that can be used to ground connect the
shield extensive. You have to remove the outer insulation of the cable
in the area of this bracket. Take care, that shielding is not damaged
during removing of isolation. Feed the cable through the bracket ad
close it by considering, that the de-insulated part fits the bracket. If
you decide to go with 1), you can nevertheless use this bracket as
strain-relief for the cables.
Actually interfaces for three types of position encoders are
available with the sat-nms ACU:
resolvers
SSI digital position encoders
analog voltage based sensors Depending on the interface type you
use, different pinouts are used. The following tables show you detailed
the pin descriptions: CON18, CON19, CON20 Resolver
Interface
Below the pinout of a resolver type interface board is shown. The ACU
is available with resolver, SSI or analog position sensor interfaces.
You have to select type of interface when you order the ACU.
pin
signal
description
type
1
GND
2
SIN
resolver SIN
IN
3
GND
resolver SIN
IN
4
COS
resolver COS
IN
5
GND
resolver COS
IN
6
REF
drive signal to resolver
OUT
7
GND
drive signal to resolver
OUT
8
GND
The ACU resolver interface is designed for resolvers with an
impedance of 100 Ohms or more and transfer factor 0.5. The interface
applies 4Veff / 2000Hz to the resolver drive coil. It expects 2Veff at
the sine / cosine inputs at the maximum positions.
resolv.gif
When connecting a resolver to the ACU, please consider the
following:
Use a shielded, twisted pair cable.
Connect the cable shield either to pin 1/8 at the
ACU or to the ground at the resolver housing. Never
connect the shield at both ends, this will introduce a ground loop and
cause a significant degradation of the resolver’s accuracy.
Below the pinout of a SSI type positional encoder interface board is
shown. The ACU is available with resolver, SSI or analog position sensor
interfaces. You have to select type of interface when you order the
ACU.
The SSI positional encoder may be powered from the ACU internal power
supply. +5V and +24V clamps are provided at the connector. To avoid
ground loops, the cable shield should be connected
either to pin 1 at the ACU or to the
ground at the encoder housing, never at both ends.
pin
signal
description
type
1
GND
2
SSI-Data+
SSI data
IN
3
SSI-Data-
SSI data
IN
4
SSI CLK+
SSI clock
OUT
5
SSI CLK-
SSI clock
OUT
6
7
+5V
encoder power supply
8
+24V
encoder power supply
CON18, CON19, CON20 Analog Angle Sensor
Interface
Below the pinout of an analog type positional sensor interface board
is shown. The ACU is available with resolver, SSI or analog position
sensor interfaces. You have to select type of interface when you order
the ACU.
