librenms-librenms/includes/discovery/sensors/frequencies/netvision.inc.php

<?php

if ($device['os'] == 'netvision') {
    $freq_oid = '1.3.6.1.4.1.4555.1.1.1.1.3.2.0';
    $descr    = 'Input';
    $current  = (snmp_get($device, $freq_oid, '-Oqv') / 10);
    $type     = 'netvision';
    $divisor  = 10;
    $index    = '3.2.0';
    discover_sensor(
        $valid['sensor'],
        'frequency',
        $device,
        $freq_oid,
        $index,
        $type,
        $descr,
        $divisor,
        '1',
        null,
        null,
        null,
        null,
        $current
    );

    $freq_oid = '1.3.6.1.4.1.4555.1.1.1.1.4.2.0';
    $descr    = 'Output';
    $current  = (snmp_get($device, $freq_oid, '-Oqv') / 10);
    $type     = 'netvision';
    $divisor  = 10;
    $index    = '4.2.0';
    discover_sensor(
        $valid['sensor'],
        'frequency',
        $device,
        $freq_oid,
        $index,
        $type,
        $descr,
        $divisor,
        '1',
        null,
        null,
        null,
        null,
        $current
    );
}