Overview

The DHD Communication Server (DHDCS), has three main tasks:

1. DHDCS is used to maintain DHD devices, e.g. to update Firmware or Kernel, to adjust network settings or to enter licenses.
2. DHDCS allows to monitor DHD systems in the same network and to log their activities. This is especially useful for monitoring certain functions in complex systems or for troubleshooting. To do so, you can use the user interface of the DHDCS to set up logging (see Logging). The generated log files may also be requested when contacting DHD support.
3. DHDCS distributes the UDP network traffic to all DHD sofware applications at the same time on the same Windows PC.

DHD systems have an Ethernet port to communicate with each other or with one or more PCs running DHD applications. For this communication, the network protocols UDP and TCP/IP are used as follows.

DHD devices uses the connectionless UDP protocol for communication with each other and between DHD devices and PCs with DHD applications. During this communication, a DHD device sends UDP packets as broadcast that are read by all recipients and evaluated if necessary. The data in the packet do not require any feedback, thus being an information to all. It is up to the recipient if he evaluates the data. The following information is broadcasted via UDP:

1. A heartbeat packet is sent each second from the DHD device. It contains information for all recipients, including device name, project ID, IP address and its Ethernet MAC address. This procedure is used for example by the Toolbox software to automatically show a list of all DSP cores available in the network.
2. Global Logic signals, Global Resources and Global Potentiometers are also transferred via UDP broadcast. Each device in the network analyses the Project ID of the sender. If this matches with the own Project ID, the payload data is evaluated further. If not, the UDP packet is discarded.
3. Certain operating conditions are also reported via UDP broadcast. This includes for example over-modulated audio inputs, communication problems of the DSP core among each others, changes of the synchronisation sources. Special DHD applications like DHDCS analyse these messages and can generate a log file.

This protocol is mainly used by DHD applications that communicate directly with a DHD device. For this, a point to point connection is set up through the network that works in both ways. Using this data channel, the DHD device can report its status to the DHD application; the software can control the DHD device. TCP connections are used for the following:

1. Toolbox software uses a TCP connection to exchange configuration data with the DHD device. The firmware of the DHD device is also updated this way.
2. DHD applications use a TCP connection to exchange data with or monitor a DHD device.
3. You can manually add DHD Devices to DHDCS (see Add Device). This will open a TCP socket between DHDCS and the DHD Device for logging.

DHD Communication Server is a self-contained software component that is integrated in all DHD applications accessing the UDP data stream. When you start a DHD application, the DHDCS starts automatically and runs in the background. If you start additional DHD applications, they also use the DHDCS which is running already. Data transfer of all active DHD applications is processed completely by DHDCS. DHDCS is only quitted when the last DHD application that is accessing it is closed as well and logging is not active.

As you can see in the figure, when the DHDCS is running, the notification area in the Taskbar shows a small DHDCS icon . A double click on this icon opens the main window of the DHDCS.

DHDCS Icon (Orange) in Windows Taskbar

The tray icon indicates network activity. Possible states of the tray icon are:

• (both triangles white): no network activity
• (upper triangle red, lower triangle white): outgoing network activity
• (upper triangle white, lower triangle red): incoming network activity
• (both triangles red): network activity incoming and outgoing
• (exclamation mark): high traffic warning