Galil DMC-2X00 user manual Input Circuit

I/O point. The numbers above the Bank 0 label indicate the number of the I/O point corresponding to the LED above it.

Digital Inputs

Configuring a bank for inputs requires that the Ux3 and Ux4 sockets be populated with NEC2505 optical isolation integrated circuits. The IOM-1964 is shipped with a default configuration of banks 2- 7 configured as inputs. The output IC sockets Ux1 and Ux2 must be empty. The input IC’s are labeled Ux3 and Ux4. For example, in bank 0 the IC’s are U03 and U04, bank 1 input IC’s are labeled U13 and U14, and so on. Also, the resistor pack RPx4 must be inserted into the bank to finish the input configuration.

Input Circuit

1/4 NEC2505

To DMC-1748* I/O

DMC-1748* GND

I/OCn

1/8 RPx4

x = bank number 0-7

n = input number 17-80

I/On

Figure A-8

Connections to this optically isolated input circuit are done in a sinking or sourcing configuration, referring to the direction of current. Some example circuits are shown below:

	Sinking		Sourcing
I/OCn	+5V	I/OCn	GND
I/On	GND	I/On	+5V
	Current		Current

Figure A-9

There is one I/OC connection for each bank of eight inputs. Whether the input is connected as sinking or souring, when the switch is open no current flows and the digital input function @IN[n] returns 1. This is because of an internal pull up resistor on the DMC-2x40*. When the switch is closed in either circuit, current flows. This pulls the input on the DMC-2x40 to ground, and the digital input function @IN[n] returns 0. Note that the external +5V in the circuits above is for example only. The inputs are optically isolated and can accept a range of input voltages from 4 to 28 VDC.

Active outputs are connected to the optically isolated inputs in a similar fashion with respect to current. An NPN output is connected in a sinking configuration, and a PNP output is connected in the sourcing configuration.

178 • Appendices DMC-2X00