Networked eDAQXR units

Networked eDAQXR units can be connected in a variety of ways. See eDAQXR eXRCPU for information about connection of an eXRCPU to other devices. The eDAQXR currently supports only one networking mode (Mode 1).

Mode 1 Networking

One eDAQXR serves as the networked system host (subsequently referred to as the master node), and all other connected eDAQXR units provide source data to the master node (subsequently referred to as slave nodes). The master node runs the test engine that processes all input channels, Computed channels and DataModes and drives the run time displays. A single SIE file is generated on the master node only.

NOTE
The eDAQXR currently supports only 2 network nodes (i.e., one master and one slave node). The nodes must both use the ETH1 port for the network connection. The ETH2 ports can be used for other device connections (i.e., MX modules or Axis cameras).

The master node is always the node used to start the test. Typically, the SXR file will reside on only one node and this will be the master node when the test is started. For the most part, the user only needs to communicate with the master eDAQXR. However, there is currently the following exception.

  1. AOX files contain scaling information for the one node only. If analog outputs are used on any slave node, they can only be downloaded by connecting to the slave node.

All test runs modes (Normal, Cyclic and Remote control) are available in a networked system. If the Remote control run mode is used, the eXRCPU IO switch 1 on the master node must be used.

CPU load balancing: For many applications, the user does not need to be concerned with this issue. However, if the CPU load of any node exceeds 60-70%, the user should consider options for balancing the CPU loads across the nodes, which requires some trial and error experimentation. Following are some guidelines.

  1. The master node will typically have the highest CPU load. It is usually best to configure the units so that the slave nodes have as many eDAQ layers as possible. Similarly, assign MX modules and Axis cameras to slave nodes. eXRCPU CAN and GPS interfaces are processed almost completely in the test engine and so it is not very important which node these are connected to.
  2. With a system configured, it is advised that the user run some check out tests with the System channel “cpu_load” added to the test for each network node. Start the checkout test and let it run for 5 minutes or so. Analyze the SIE data for these channels to assess the load balancing and decide if further action is required.
  3. Bear in mind that adding run time displays will place additional (and often significant load on the master CPU). As such, if these are not already defined in the checkout tests, attempt to configure the test so that the master node CPU load is a minimal as possible.