Control Logic Polarity Switch (S2); Relay Power-Up State Switch (S3); Screw Terminals - Measurement Computing USB-SSR08 User Manual

USB-SSR08 User's Guide

Control logic polarity switch (S2)

Switch is a four-position switch that sets the control logic polarity for each module group for either inverted
S2
(active high) or non-inverted (active low, default). You can use InstaCal to read the current logic configuration
for each module group.

Relay power-up state switch (S3)

Switch is a four-position switch that sets the state of the output relays at power-up. You can use InstaCal to
S3
read the current resistor configuration for each module group. Fi
default settings (modules inactive on power-up).

Screw terminals

The USB-SSR08 has eight screw terminal pairs to connect external devices to the SSR modules. Two terminals
are dedicated to each module (one positive and one negative terminal). Each screw terminal is identified with a
label on the board and on the underside of the enclosure lid.
Caution! Before connecting wires to the screw terminals, turn off the power to the USB-SSR08, and make
sure that the signal wires do not contain live voltages.
Use 12-22 AWG wire for your signal connections. Properly insulate the wires to avoid any short circuit to the
other channels, ground, or other points on the board.
Caution! Keep the length of stripped wire at a minimum to avoid a short to the enclosure! When
connecting your field wiring to the screw terminals, use the strip gage on the terminal strip, or
strip to 5.5 - 7.0 mm (0.215" to 0.275") long.
Figure 3-3 shows switch S2 configured with its default settings.
NON
INVERT
Figure 3-3. Switch S2 default configuration
P/UP
Figure 3-4. Switch S3 default configuration
Figure 3-5. Screw terminals
CH
CL
S2
INVERT
gure 3-4 shows switch S3 configured with its
P/DN
CH
CL
S3
3-3
Functional Details