Design of a signal-oriented automatic test system resource allocation method

Abstract: Aiming at the problem of poor portability of TPS in ATS, this paper studies the structure of signal-oriented automatic test system under the ATML framework, and proposes a signal-oriented automatic test system resource allocation method. This method uses signals as the interface for information transmission in the test system, and allocates instrument resources to UUT ports through signal matching, which solves the problem that traditional instrument-oriented automatic test system resource allocation depends on hardware resources, and improves the portability of TPS.

  0 Preface

ATS (Automatic Test System, automatic test system) can automatically test the equipment under test, fault diagnosis. The TPS (Test Program Set) developed in the traditional instrument-oriented ATS involves direct access to test resources. When TPS is transplanted between different platforms or the test instrument resources are changed, the test program needs to be changed a lot. Poor portability and reusability.

ATML (Automated Test Markup Language, automatic test markup language) adopts a signal-oriented structure for standardized description of ATS.

ATML describes the test requirement as the measurement/stimulus signal requirement of the UUT port, and the test resource capability describes the signal capability of the instrument resource port. The allocation of instrument resources is realized through signal matching. During the test execution, the test program calls the signal-oriented instrument driver to implement the test operation according to the result of the instrument resource allocation. The TPS developed based on ATML does not contain any operations for hardware resources. When TPS is transplanted between different platforms, the resource allocation module can re-allocate test instruments for UUT ports, which improves the portability of TPS.

1 Description of instrument capability

The ATML ATS relationship diagram is shown in Figure 1.



In ATS, the main function of the instrument is to generate or measure the demand signal of the UUT port. Traditional test instruments are often dedicated instruments with a single function. There are a large number of instruments in the ATS. With the increase of the equipment under test, there are more and more dedicated test adapters, which leads to the larger and larger scale of the general-purpose ATS. In recent years, there has been a software-controlled synthetic instrument technology that is realized in a combination of functions, such as Ai7 technology, which implements the functions of 7 instruments by a synthetic instrument module. Each channel of the reconfigurable instrument resources independently developed by this unit can be software-defined as AD/DA/counter/DMM and other commonly used test instrument resources, eliminating the resource allocation link (signal switch matrix); at the same time, the reconfigurable instrument has Ultra-wide range, signal conditioning can be performed without using an interface adapter.

In order to realize the flexible reloading of the TPS for signal development and the independence of the instrument, ATML does not directly use the physical ports (Ports) of the instrument, but defines the signal capabilities (Capabilities) and logical resources (Resources) in the instrument description file. The resource-to-resource mapping (Capability-Map) and the resource-to-port connection (NetworkList) realize the allocation of different signal capabilities to the instrument ports. The capability of the entire test system is the sum of the capabilities of all instruments in the test workstation.

Take the multimeter resource in the reconfigurable instrument as an example, the mapping relationship between its capabilities, resources and ports is shown in Figure 2.



(1) Define the signal capability of the instrument

The signal capability of the instrument defines the signal type information that the instrument can generate or measure. The signal capability of the instrument is described using STD's BSC (BasicSignal Component) library and TSF (Test SignalFramework) library. You can also use the combination of the basic signals in the BSC library and TSF library to customize the complexity of the test. signal. Take the DC voltage measurement capability as an example, the amplitude range is -400~400 V, and the accuracy is 0.1%. The ATML description is as follows:



(2) Define logical resources

Logical resources define the functional modules inside the instrument, which are used to connect the signal capability and physical ports of the instrument. The multimeter resource shown in Figure 2 contains 4 logical ports: P1, P2, P3, P4.

(3) Define the physical port of the instrument

The physical port defines the external port of the instrument, the port in Figure 2:

HI, LO, Sense_HI, Sense_LO.

(4) Map signal capabilities to resources

The CapabilityMap element is used in the instrument description document to describe the mapping relationship between signal capabilities and logic resources. Its structure is: Capability-Map/Mapping/Map/Node/Path. By adding Mapping elements to map multiple signals to the same resource, it can be described that one resource can generate/measure multiple signals, but it can only generate/ Measure one of the signals; by adding a Mapping element to map a signal to multiple resources, it can be described that a signal can be generated/measured by multiple resources; by mapping multiple signals to a resource in the same Mapping element, it can be described A resource can generate/measure multiple signals at the same time; by mapping a signal to multiple resources in the same Mapping element, it can describe that a signal occupies multiple resources; by adding multiple Map elements to the same Map-ping element, you can Describe the connection of multiple ports between signals and resources; by adding multiple Node elements to the same Map element, one-to-many or many-to-one connections between signals and resources can be described; Path element is used to describe capabilities or resource ports in the instrument Describe the location in the document. Through the above combination, it is possible to complete the description of complex relationships such as interdependence or constraints among specific instrument functions.

(5) Connect resources to physical ports

The NetworkList element is used in the instrument description file to describe the connection relationship between logical resources and physical ports. Its structure is: NetworkList/Network/Node/Path. By adding Network element, it describes multiple logical connection lines between resources and ports; Path element is used to describe the position of resource ports and physical ports in the instrument description document.

2 Description of test requirements

ATML uses STD to describe the test requirements in the test description document. The excitation signals or measurement signals required by all ports and test points of the UUT are described in the element TestDescription/DetailedTestInformation/Action/Behavior. The structure of the Behavior element is shown in Figure 3.



Operations elements and IeeeStd1641 elements contain references to STD standards. Take the Operations element as an example to illustrate the description method of test requirements in ATML. The Operations element uses 17 predefined types of operations (Operation) to describe the behavior of Behavior. Among them, the OperationSetup type of operation is used to create a demand signal, and the Opera-tionConnect type of operation is used to connect the signal to the UUT port or test point. Use the OperationConnect operation to connect the signal signal1 created in OperationSet-up to a certain port of the UUT, which can describe the demand signal of this port of the UUT as the signal1 signal.

3 Instrument resource allocation module design

The instrument resource allocation module realizes the mapping of instrument resource ports to UUT ports by signal matching between test requirements and test resource capabilities. UML (Unified Modeling Language, unified modeling language) is used to describe the design scheme of the instrument resource allocation module, and its use case diagram is shown in Figure 4.



In the instrument resource allocation module, by loading the test description file, the test workstation description file and the instrument description file, the test requirement information and the test system capability information are obtained, and the instrument resource allocation is realized through signal matching.

Through the analysis of Figure 4, the use case is abstracted, and the class diagram of the instrument resource allocation module is shown in Figure 5.



A brief introduction to the classes involved in the class diagram is as follows:

(1) Instrument resource management: allocate instruments according to the signal requirements of each UUT port and the instrument capability list, generate instrument working mode configuration information, and obtain the connection relationship between the workstation and the UUT according to the connection relationship between the instrument and the test workstation, and finally generate the UUT The physical connection information from the port to the workstation port.

(2) Instrument category: Load the ATML document of the instrument description, parse the document to obtain instrument capabilities, logic resources, instrument ports, and capability-to-port mapping information; generate instrument working mode configuration files based on the results of instrument resource allocation.

(3) Test description category: Load the test description description ATML document, parse the document to get UUT port, test point and demand signal information.

(4) Test workstation category: Load the ATML document describing the test workstation, and parse the document to obtain the test workstation port, instrument resource information, and connection information between the instrument and the workstation.

(5) Physical connection category: Generate the physical connection file from the UUT port to the test workstation port according to the result of the instrument resource allocation.

Through the analysis of the static model of the instrument resource allocation module, the sequence diagram of the interaction of system objects over time is shown in Figure 6.



It can be seen from Figure 6 that the process of instrument resource allocation is: parse the test description file to obtain the demand signal of each port of the UUT; parse the test workstation description to obtain all the test instrument information in the workstation and the connection relationship between the instrument and the workstation; parse the instrument description file , Get the instrument capability list and the connection information of the instrument capability to the instrument port; assign the instrument according to the signal requirements of each port of the UUT and the instrument capability list, generate the reconfigurable instrument working mode configuration file, and obtain the workstation according to the connection relationship between the instrument and the workstation The connection relationship with the UUT, the physical connection file from the UUT port to the test workstation port is generated.

In the form of an activity diagram, the operation of allocating instrument resources is explained, as shown in Figure 7.

The process of allocating instrument resources is as follows:

(1) Query the UUT port demand signal list, and obtain the UUT port UUT_Port demand signal R_Signal; if the list is empty, exit;

(2) Query the signal capability list and obtain the signal capability A that meets the demand signal R_Sig-nal; if it fails, the R_Signal is not matched successfully, and the current test configuration cannot meet the test requirements, go to (1);

(3) Query the CapabilityMap list to obtain the mapping Mapping containing signal A; if it fails, go to (2);

(4) Obtain the resource R for generating/measurement signal A by mapping Mapping;

(5) Check whether the resource R is free from the resource list. If the resource R is used, go to (3); if the resource R is free, go to (6); if the resource R is free (that is, the resource R can generate/measure more Kinds of signals, and one or more of them have been generated/measured using resource R), go to (7);

(6) Query the NetworkList list of the instrument, obtain the instrument port INST_Port connected to resource R; query the NetworkList list of the test workstation, obtain the workstation port Sta_Port connected to INST_Port, and generate the connection between Sta_Port and UUT_Port; the test instrument calls the signal-oriented corresponding to the signal capability A The instrument driver of the INST_Port port generates/measures the demand signal R_Signal of the UUT_Port port; go to (1) to continue to match the next item;

(7) Query the connection list of resource R and instrument ports, workstations, and UUTs, and obtain the connected UUT port R_UUT_Port of resource R; compare UUT ports UUT_Port and R_UUT_Port, if they are the same, use UUT_Port connected instrument to generate/measure signals R_Signal, go to (1) to continue to match the next item; if the two are different, go to (3).

When there are multiple instruments to meet the test requirements, the instruments should be sorted according to certain principles to determine the final selection of test instruments. You can refer to scheduling methods such as accuracy, balanced use of the instrument, and use habits of the instrument for testing.



4 Conclusion

This paper studies the signal-oriented description method of test system capabilities and test requirements in ATML, and gives specific description examples; uses UML to design the software structure of the instrument resource allocation module in detail. The instrument resource allocation module allocates instrument resources for the UUT's ports to be tested by matching the test system capabilities and test requirements. The signal-oriented resource allocation method improves the portability of TPS in ATS. The method proposed in this paper can provide guidance for other similar researches. (Author: Zhang Wen, Yang Jingli)