14
LOGIC INPUTS
Eight Logic Inputs are available on a rear panel 9-pin Sub-D (female) connector. Logic Inputs allow remote control of the SPM723 via
external circuits, such as switches, contact-closures, active driver circuits, and/or ‘open-collector’ logic outputs. From the factory, Logic
Inputs 1~8 have no pre-programmed function. However, each Logic Input may be assigned different ‘actions’ using the BiampWin
software and serial cable provided with the SPM723 (see Setup on pg. 9). Since Logic Inputs are controlled by switches, contact-closures,
etc., each Logic Input may be assigned two functions (one for switch ‘closed’ and one for switch ‘open’).
Logic Inputs have the following pin assignments (right-to-left & top-to-bottom
): Pins 1~8)
Logic Inputs 1~8;
Pin 9)
Ground.
pin #1
= Logic Input 1
pin #2
= Logic Input 2
pin #3
= Logic Input 3
pin #4
= Logic Input 4
pin #5
= Logic Input 5
pin #6
= Logic Input 6
pin #7
= Logic Input 7
pin #8
= Logic Input 8
pin #9
= ground
logic inputs
1
2
3
4
5
6
7
8
9
When nothing is connected to a Logic Input, an internal pull-up resistor keeps it at a ‘high’ idle state (+5.0 VDC). The Logic Input is
activated when its input goes ‘low’ (less than +0.8 VDC), and is de-activated when its input goes ‘high’ (greater than +2.4 VDC). A Logic
Input is controlled in one of three ways: 1) Use an NPN style ‘open-collector’ logic output from an external device (such as a BIAMP
PMX84 or DRC4+4) to short the Logic Input to ground. 2) Use a switch, relay, or other contact-closure (such as from a third-party
controller) to short the Logic Input to ground. 3) Use an active TTL output driver circuit (such as from a third-party controller) to actively
drive the Logic Input to a ‘high’ or ‘low’ state.
Multiple contact-closures or ‘open-collector’ logic outputs may be wired in parallel to a single Logic Input (see diagram below). Logic
Outputs and contact-closures should be rated for at least 5 Volts / 1mA operation. Low-current / dry-contact closures are recommended
for reliability. Active output driver circuits should not exceed a signal range of 0~5 Volts DC, and should have a minimum pulse width of
100 milli-seconds. Logic Input impedances are approximately 10k ohms.
multiple switches to single Logic Input
