eBIRST tools allow the measurement of path resistance between any two pins of a switching system connector, but this is not always adequate to test a switching system. For these applications a master slave arrangement is required.
Example of system requiring Master Slave tools
An example of the need to have master slave tools is the Pickering Interfaces 40-570, a BRIC which is designed to be a MUX rather than the more normal matrix. There are many other examples as well.
40-570 is an example of a PXI switching system that has multiple connectors and thru paths between the connectors that need relays testing. In this example each connector carries 160 pin forming a MUX with the common on one connector and loop thru and outputs on other connectors
An input connection can be connected to any one of a number output connectors, the arrangement being particularly convenient when a test system needs to be connected to one of a number of test targets. As each test target is on a different connector to the test system cabling is made relatively easy, in many cases allowing the user to use off the shelf cables rather than having to design custom cables.
This clearly creates a test problem, to measure a path resistance you have to connect to two (or more) connectors. That requires two test tools working together.
Master Slave eBIRST Operation
When two eBIRST tools are used to make a path measurement across different connectors one is designated as the master and the other as the slave.
Master slave operation where two tools work together, the master selects one path and does the measurement, the slave selects the second path and routes it to the master thru the master slave cable
Both tools are connected to USB ports on the controller, the tools are physically identical. A cable is then used to connect the tools together, a master slave cable. The cable carries a simple analog bus that enables the measurement engine on the master eBIRST tool to connect two of its four terminals to the slave tool and for the master to perform all the measurements. The test program designates which tool is the master and tells the user where to connect the two tools. The application program manages all the issues, the user just follows the instructions that are provided by the program as on screen prompts. The tools deal with the calibration issues as well by using the master's internal calibration information.
The two switching system connectors need not be the same, you can connect one tool to one connector and a different tool (or tool and adapter) to another of a different type. The master slave cable is common to all tools. All the user needs to do is to make sure they have the tools corresponding to the two required connectors.
The master slave connection is protected so that if one tool is powered up and the other is not then no damage will occur, though of course a test cannot be performed in this state.
The master slave arrangement on eBIRST allows the testing of switching systems where a connection path needs testing that passes from one physical connector to a second physical connector. The application program handles the two tools so that one is the master and performs the measurements and provides access to the first connector while the other is a slave and provides access to the second connector.