Weidmuller GPRS Alarm Unit - Manual (Page 78)

Hardware
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5.6 Status display
Three LEDs are located on the front panel of the IE-GPRS-I/O to
display the operating status. To display the status of the port, 12 further
LEDs are installed on the upperside/underside of the device to display
the states of the digital inputs/outputs.
Status of the GPRS/GSM communication
Voltage level at the
digital inputs/outputs
Mode selector switch
Operating state of the IE-GPRS-I/O
Status of the operating voltage