public void setFrequencyModeAsString(String frequencyMode) {
   frequencyMode = Val.chkStr(frequencyMode);
   try {
     this.frequencyMode = FrequencyMode.valueOf(frequencyMode.toUpperCase());
   } catch (IllegalArgumentException ex) {
     this.frequencyMode = FrequencyMode.PERIODICAL;
   }
 }
 public String getFrequencyModeAsString() {
   return frequencyMode.name();
 }