LMX SERIES™ OPERATION MANUAL
SECTION 7: Auxiliary I/O
Error! Reference source not found.
Entire Contents Copyright
2018 by Pacific Power Source, Inc. (PPS) • All Rights Reserved • No reproduction without written authorization from PPS.
LMX Series Power Source Operation Manual
Page 190 of 463
Digital outputs 1 and 2 are TTL level signals (0 to 5V), and digital outputs 3 and 4 are open-
drain type outputs (with an internal pull-up) that can be used to drive external relays. Each
open-drain output has a current protection of 0.5A and internal clamping diode prepared to
drive a relay coil.
See section 8.10.1.4 for commands that configure and read digital outputs.
7.8
Analog I/O Descriptions
Both analog inputs and outputs are available on the AUX I/O feature. Analog inputs are
used to change output parameters such as voltage or frequency. Analog outputs are
provided to allow monitoring the LMX measurements using external equipment.
The analog inputs can be repurposed from level programming input to direct analog inputs
as needed. Refer to section 7.9, “Analog Input Modes” on page 192 for details.
7.8.1
Analog Inputs
ANALOG
INPUTS
FREQ (Hz)
AMPL (V)
There are 4 analog inputs that accept DC signals up to 10Vdc and may be used to program
the LMX output parameters such as voltage, frequency, current and power limits.
These inputs are sampled 20 times per second so updates of the assigned parameters occur
at this rate. The full-scale range of the analog inputs can be programmed to be 5V, 10V or
any value between 1 and 10V.
Note:
Once enabled, make sure the input is not left floating or a small offset of about 2 to
3 % of full scale may be present affecting the programmed parameter. For example,
when programmed to control AC voltage, no input on the analog input assigned will
result in an output voltage of about 0.02 to 0.03 x 300 = 6 to 9 Vac.
The full-scale value for voltage programming depends on the selected operating mode. A
10V input represents 300Vac RMS.
For frequency programming, 0V represents 15Hz while 10V represents 5000Hz.
These analog inputs are all disabled by default. In order to use this feature, each analog
input has to be assigned to an LMX parameter and phase, for example AC voltage of phase
A.
