Chapter 4. Connection Of Signals; Gnd, Dgnd, Agnd Circuits; L-502 Connectors Description; L-502 External Signal Connector - L-Card L-502-P-G-D-I User Manual

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Chapter 4.
This chapter provides information on the L-502 connectors, the assignment of their contacts,
and the main characteristics of the L-502 inputs and outputs related to the correct connection.

4.1. GND, DGND, AGND circuits.

L-502 has the following the following conventions for earth circuits (or "common wire"
circuits for an interface):
GND is the ground circuit of the computer's system unit, electrically connected to the
computer chassis, with the computer's mains plug ground, the GND circuit of the computer's
motherboard, with the GND PCI Express circuit.
AGND is a "common wire" circuit of analog circuits: ADC inputs and DAC outputs.
DGND is a circuit of the "common wire" of digital circuits: digital inputs and outputs.
!
In any modification of the L-502, the AGND and DGND circuits have a common
connection point inside the L-502
In L-502-░-X-░ (without galvanic isolation) the GND circuit has an internal connection
point with DGND, which in turn is connected to AGND.
In L-502-░-G-░ (with galvanic isolation), DGND-AGND circuits are isolated from
GND and all other circuits of the computer, and the DGND and AGND circuits have a
connection point inside the L-502.

4.2. L-502 connectors description.

4.2.1. L-502 external signal connector.

The external signal connector is a 37-pin 2-row type DRB-37M plug that extends outward
when the L-502 module is installed inside the PC unit. The bracket L-502 is directly fixed to the
DRB-37M connector with 6-point screws.
The conductive contact of the connector (screen) is always electrically connected to the
computer case (GND circuit).

4.2.2. Connecting the cable shield.

On the casing of the cable part of the DB-37F signal connector it is possible to directly seal
the screen of the signal cable for any modification of the L-502, however, as shown by the L-502
practice, the best signal-to-noise ratio is obtained by connecting the cable shield to the AGND
signal connector (there are no connections to the connector housing).
Connection of signals.
4.1: GND, DGND, AGND circuits.