MOTOTRBO: What does DDMS do?

Device Discovery and Mobility Service (DDMS) is a Windows application that runs as a service (i.e. it starts automatically when Windows boots and runs in the background). It processes the presence and mobility information from radios on a MOTOTRBO radio system.

Depending on how it’s configured, a MOTOTRBO radio will send an ARS (Automatic Registration Service) message whenever it powers on; when the user changes channel or when the radio roams to another site. The ARS message contains the radio ID number and (if applicable) some information about which site and timeslot was used to send the ARS.

The ARS message is sent to a predefined radio ID in the system. This would be the ID of a Control Station or MNIS (Motorola Network Interface Service). A Control Station is essentially a MOTOTRBO radio connected to a computer via USB data cable*.

MNIS is also a Windows application that runs as a service. It acts as a virtual radio, as well as a bridge between the IP network and the radio system. If you use MNIS, you generally don’t need Control Stations. This would be useful in some situations as a Control Station needs to be connected to a computer and both need to be within RF range of the radio users.

When used with DDMS, MNIS will receive ARS messages and pass this to DDMS, which retains the mobility and presence information of all active radios. An application, like MOTOTRBO Radio Management, can use DDMS to determine if a target radio is online before performing an OTAP job.

The DDMS settings in MOTOTRBO Radio Management (PN Server)

If a radio turns off, it makes a best effort attempt to send a ARS message. If something goes wrong (e.g. the user pulls the battery off without switching off), no ARS will be sent. To keep the presence and mobility information fresh, DDMS can be set to remove the details of radios not seen for a period of time.

ARS and DDMS are not needed in Capacity Max - this uses DMR Tier 3 standard registration and a trunking controller to manage the presence and mobility information.

* Bluetooth can be used in place of the USB cable but is not recommended for remote installations.