30
ZABER TECHNOLOGIES INC.
10.1. Digital Inputs
The digital inputs on the X-MCB2 are fully opto-isolated and bi-directional, giving added flexibility
when interfacing to external equipment. The two examples below demonstrate how the common
line can be connected to a power rail or to ground, depending on the application.
Each digital input contains an internal current limiting resistor of 442 ohms. While this value is
suitable for driving the inputs with 5V (as shown in the circuit above), higher voltages will require
the addition of a series resistor. A list of recommended values for the external resistor and
example circuit are shown below.
V_SUPP (V)
R_EXT (Ohms)
Power (mW)
0 - 8
0R
n/a
8 - 15
500R
125mW
15 - 24
1500
250mW
The circuit above also shows how to interface with an open collector output from another device.
