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Power supply and consistency requirements of vehicle OBD diagnostic instrument
Time:2021-12-17 Read: 981

1、 Power requirements

1. The external test equipment only supports 12V DC battery voltage.

If the external test equipment only supports 12V DC battery supply voltage of the vehicle, the following requirements shall be met:

(1) It can be used normally within the voltage range of 8V to 18V DC vehicle battery;

(2) The vehicle battery voltage can operate normally for less than 10 minutes at 24V DC;

(3) When the voltage is up to 24V (DC), the vehicle can run for 10 minutes with less battery under non-working condition.

When the engine is started, the vehicle voltage will be reduced to 5.5 V, but the duration will be as long as 0.5 s. Communication and data transmission will not be interrupted. During this period, there is no need to display. This is not a compliance requirement.


2. The external test equipment supports 12V and 24V DC battery voltage.

If the external test tool supports 12V and 24V DC battery supply voltage of the vehicle, the following requirements shall be met:

(1) It can be used normally within the voltage range of DC vehicle battery from 8V to 32V;

(2) The battery voltage of 36V DC vehicle can operate normally for less than 10 minutes;

(3) When the voltage is up to 36V (DC) in non-working state, the vehicle can run for 10 minutes with less battery.

According to ISO 16750-2, when the engine is started, communication and data transmission will not be interrupted during the process of reducing the vehicle battery voltage. During this period, there is no need to display. This is not a compliance requirement.


3. Battery current

The maximum current drawn by the external test equipment through the power contact of the diagnostic connector shall not exceed the maximum current specified in ISO 15031-3, that is, the minimum current carrying capacity provided by the vehicle.


4. EMC (electromagnetic compatibility)

The external test equipment shall not interfere with the normal operation of the vehicle electrical system. The normal operation of external test equipment shall not be affected by the moving environment and the conduction and radiation when connected with the vehicle. Electromagnetic compatibility and electrostatic discharge measurements and limits shall comply with the current standards of the country where the tester is sold.


2、 Consistency test

The conformity test specifies the tests to be passed by the external side test equipment for type approval according to ISO 15031-4. Only external test equipment that has passed all tests can be labeled test equipment, and the equipment should support all listed protocols that the equipment will be provided to the market and allowed by national laws.


The manufacturer of external test equipment can optimize the automatic determination of communication interface sequence, which only applies to the protocols allowed by national and regional legislation. For example, if the country only allows 500 kbps of CAN data rate (although the standard allows 250 kbps), the external test equipment manufacturer can only support this baud rate.


The verification of the conformity test is the responsibility of the equipment manufacturer. Each sample unit test of the equipment manufacturer shall be successfully conducted for five consecutive times before it can be considered as passed.


All changes in the hardware or software used in the external test equipment should be retested, or the manufacturer of the external test equipment should explain why it is not necessary to retest.


If an explanation is submitted in the test due to changes, the organization that initially conducted these tests should determine whether the explanation is acceptable or whether it needs to be retested. In determining whether to accept the description of each product type, reasonable normal engineering standards shall be used.


The product type label shall meet or be compatible with the requirements of ISO 15031-4 OBD access equipment, and the manufacturer shall record the following contents:

(1) Specify the hardware version, software version and supported protocol version of the product;

(2) Methods for conducting these tests;

(3) Test results.


In these tests, correct and incorrect response messages will be used. The error response of ISO 15031-5 is a response with incorrect header information, incorrect SID, incorrect PID, incorrect response message length or incorrect CRC or checksum. J1939's incorrect responses are those with incorrect address or message label, incorrect parameter identification, correct response message length, or incorrect CRC or verification. The external test equipment must ignore all incorrect response information.


The test will involve multiple electronic control units responding to a single request message, multiple electronic control units responding to a single request message, and multiple electronic control units responding to a single request message.


The interval between the end of the request message and the beginning of the response message will change from 0 milliseconds to the delay required to display the non-response message indication on the external test device. The delay resulting in the indication of no response information will be compared with the value defined in ISO 15031-5 or the value defined in SAE J1939-21 specification.


Test to determine whether the format, content and sequence of the information transmitted on the data link are correct and meet the protocol requirements. The test shall be conducted at a temperature of (23 ± 5 ℃) and a relative humidity of 25%~95%.

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