Add error message when rig is not turned on that mentions auto_power_on

src/rig.c

@@ -1280,7 +1280,12 @@ int HAMLIB_API rig_open(RIG *rig)
             powerstat_t powerflag;
             status = rig_get_powerstat(rig, &powerflag);
 
-            if (status == RIG_OK && powerflag == RIG_POWER_OFF && rig->state.auto_power_on == 0) { return (-RIG_EPOWER); }
+            if (status == RIG_OK && powerflag == RIG_POWER_OFF && rig->state.auto_power_on == 0) 
+            { 
+                rig_debug(RIG_DEBUG_ERR, "%s: rig power is off, use --set-conf=auto_power_on if power on is wanted\n", __func__);
+
+                return (-RIG_EPOWER); 
+            }
 
             // don't need auto_power_on if power is already on
             if (status == RIG_OK && powerflag == RIG_POWER_ON) { rig->state.auto_power_on = 0; }