Matrix Orbital LK204-25 Legacy - Manual (Page 15)

Figure 17: Protocol Select Jumpers
2.4 General Purpose Outputs
A unique feature of the LK204-25 is the ability to control relays and other external devices using a
General Purpose Output, which can provide up to 20 mA of current and +5Vdc from the positive side of
the GPO. This is limited by a 240 ohm resistor which is located to the above right of the GPOs as pictured
below in
figure 21 . If the device, which is being driven by a GPO, requires a relatively high current (such as
a relay) and has an internal resistance of its own greater than 250 ohms, then the 240 ohm resistor may be
removed and replaced with a Jumper.
- (right) GND
+ (left) MAX: 20 mA, +5Vdc
Figure 18: General Purpose Output
WARNING If connecting a relay, be sure that it is fully clamped using
a diode and capacitor in order to absorb any electro-motive force (EMF)
which will be generated.
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