How to test the stability of GPRS module in detail? 0? three

what do you think? Because GPRS DTU is mainly used in remote monitoring places, the stability of GPRS DTU becomes very important. In 2003, GPRS DTU products appeared in the market, but these products were not mature, which caused great losses to users, brought a bad reputation to GPRS DTU and limited its market development. In 2006, a truly mature and stable GPRS DTU product appeared in the market, and the situation improved, and the application market of GPRS industry began to develop steadily. In 2008, TCP/IP protocol was generally embedded in GPRS core module, which lowered the technical threshold. However, many manufacturers take advantage of this convenience to introduce GPRS DTU without a deep understanding of GPRS communication technology, and their products have various performance hidden dangers. Many users choose GPRS DTU, and it is not enough to do some simple tests in the early stage. If you choose and widely use the unstable GPRS DTU, it is equivalent to planting a time bomb for your own monitoring system! How to test the stability of GPRS DTU comprehensively and quickly from the beginning? This has become an important topic! Unfortunately, most GPRS DTU manufacturers only publicize the good stability of their products, but they remain silent about the specific stability testing methods! Here, it is a verified GPRS DTU stability test process, hoping to help users master a comprehensive and operable GPRS DTU identification method, which can make many poor quality GPRS DTUs show their true colors! 1) Online Idle Test Reason: Test the ability of GPRS DTU to maintain the established link. When there is no data, GPRS DTU keeps the connection through heartbeat, and GPRS DTU should keep the average link duration of at least 1 hour without disconnecting and reconnecting. Test method: let GPRS DTU connect to the data center without sending any data, and observe how long it can keep the link, the longer the better. At the end of the test, several data packets should be sent to the data center and DTU respectively to verify that the idle link maintained by DTU is really available. If DTU or data center can't receive the data packet from the other end, it will fail. 2) Resume testing after the data center is closed. Test reason: In the future operation and maintenance of the data center, the service will definitely be temporarily interrupted, so it is necessary to test the quick recovery ability of GPRS DTU after the data center is restored. Test method: 1) Shut down the data center for a short time, for example, 1 minute, and then restore the data center to see if the DTU can connect quickly. The recovery time should be within 5 minutes, and the sooner the better. Repeat this test several times, and DTU must be able to restore the connection at 100%. As long as DTU can't restore the connection once, it is unqualified. 2) Shut down the data center for a long time, such as 60 minutes, and then restore the data center to see if the DTU can connect quickly. The recovery time should be within 5 minutes, and the sooner the better. Repeat the test several times, and DTU must be able to restore 100% connection. As long as there is a phenomenon that DTU can't restore the connection all the time, it is unqualified. 3) Frequent bidirectional small data volume test reason: Test the ability of GPRS DTU to send and receive small data packets frequently, because in daily operation, it is mainly to send and receive small data packets frequently in both directions. Test method: At the data center and DTU end, send a data packet of about 100 bytes to the other side every10 second for 30 minutes, and make statistics to find out whether there is network disconnection and data packet loss between the two sides. The best result is that there is no disconnection and reconnection, and no packet loss. If the DTU is disconnected, it will never be able to go online again, or it will not be able to continue sending and receiving in both directions after going online. Tip: Serial ports 2 and 3 of DTU can be shorted to form a loop test, and bidirectional test can only be carried out when it is sent in the data center. 4) Two-way big data stress test reason: Some applications need to temporarily transmit a large amount of data, so this test is also very necessary. Test method: In the data center and DTU, send a data packet of about 1000 bytes to the other party every 2 seconds for 30 minutes, and count whether there is network disconnection and packet loss between the two parties. Generally speaking, in the stress test, GPRS DTU may disconnect and reconnect and lose data packets. However, the number of disconnections and reconnections should not exceed 10, and the smaller the number, the better. If the DTU is disconnected, it can no longer go online, or it can no longer send and receive data in both directions after going online, it is unqualified. 5) antenna test reason: At some sites, GPRS/GSM signals may be temporarily interrupted or weakened due to some reasons at the previous site. After the signal returns to normal, GPRS DTU should be able to automatically restore the connection and continue to transmit data to the data center. Test method: 1) Dismantle the antenna in a short time: when the GPRS DTU is online, dismantle the antenna of the GPRS DTU 1 minute, and then reinstall the antenna. When the antenna of the GPRS DTU is dismantled, submit three data packets of about 100 bytes to the GPRS DTU in turn. When the antenna is plugged in, the GPRS DTU must be able to restore the connection automatically and quickly, and the sooner the better, and can continue to transmit data to the data center during this period. If all three data packets are lost, they are unqualified, and it is better to upload them all. 2) Dismantle the antenna for a long time: When the GPRS DTU is online, dismantle the antenna of the GPRS DTU for 30 minutes, and then reinstall the antenna. After inserting the antenna, GPRS DTU must be able to automatically restore the connection, and the recovery time should be less than 10 minutes. If the connection is not restored for more than 30 minutes or more, it is unqualified. 6) Reasons for repeated power-on test: Sometimes, there will be temporary power failure and then recovery, and GPRS DTU should ensure reliable login to the data center. Test method: turn on GPRS DTU, and then wait for GPRS DTU to connect to the data center. Each DTU can log in to the data center within 2 minutes and repeat the test 20 times. Once it is found that DTU can't connect to the data center all the time, it is unqualified. If conditions permit, the number of tests can be increased. VII) Reasons for interference test of dialing and short messages: During DTU login or online operation, some unknown short messages or phone calls may be received, and GPRS DTU shall ensure that these situations will not affect its normal work. Test method: Turn on the power of DTU, then wait for about 10 second, and start sending two short messages and two phone calls to DTU. DTU should be able to connect to the data center correctly. After successfully connecting to the data center, send 2 short messages and 2 phone calls to DTU, observe for 5 minutes to see if DTU can keep the link, and then send the 10 packet in both directions to see if it can receive and send normally. Viii) Watchdog test (optional test) Test reason: If a GPRS DTU passes all the previous test items, if its internal watchdog is not well done, it will be a hidden danger, and if it runs continuously in the field, it is likely to have problems. Test method: There are many test methods for watchdog. Generally, on the data bus or address bus of the internal CPU, several pins are short-circuited instantly, which causes the program to deviate or the ram data to be disordered. External strong interference sources can also be used for interference. In this case, the CPU of the product with good watchdog mechanism can be reset within 20 seconds. If it cannot be reset, it is unqualified. To test this project repeatedly, DTU must be able to reset 100%. This function requires testers to be familiar with the DTU motherboard, and the operation is not necessarily convenient, so it is set as an optional test item. However, if there are test operating conditions, this test is recommended. IX) Card pull-out test (optional test) Test reason: If the application environment of GPRS DTU is harsh, such as vibration or corrosive gas, which may lead to poor contact of SIM card for a short time, GPRS DTU should be able to recover automatically. We use temporary card removal to simulate this situation. Test method: When the GPRS DTU is connected to the data center, pull out the card for about 3 seconds, and then insert the card to see if the GPRS DTU will disconnect and send and receive data normally. Take out the card for about 60 seconds, then insert it to see if the GPRS DTU will disconnect. If the DTU can no longer be automatically connected to the center after the card is temporarily removed and loaded, it is recommended not to use this DTU in the environment with vibration or corrosive gas on site. X) Power supply fluctuation test (optional test) Test reason: If the GPRS DTU application site is powered by battery or solar energy, there may be a wide range of power supply fluctuation, and GPRS DTU should be able to adapt to this power supply fluctuation. Test method: Take 12V battery as an example, the voltage fluctuation range may be between 5V and 14V, so when we connect GPRS DTU to the data center, the external power supply will slowly rise and fall from 3V to 16V to simulate the charging and discharging of the battery. It is normal for GPRS DTU to reset in this test. We mainly check whether GPRS DTU can no longer connect to the data center. If the DTU can no longer be automatically connected to the center after power fluctuation, it is not recommended to use this DTU in the field battery-powered environment. XI) Reasons for arrearage test (optional test): During the perennial operation of DTU GPRS, it is very likely that the SIM card is in arrearage, resulting in the inability to use GPRS services, thus interrupting the communication connection. After charging, GPRS DTU shall automatically restore the connection with the center. Test method: find a SIM card with arrears and insert it into GPRS DTU, and wait 10 minutes. Due to arrears, DTU cannot log in to the data center. At this time, dial this number with your mobile phone, indicating that you have stopped or restricted incoming calls. Then recharge the SIM card, and then dial this number with your mobile phone, indicating that the card has been recharged successfully and the GSM service has been restored. Wait about 10 minutes to see if DTU can automatically connect to the data center. If DTU can't connect to the data center by itself all the time, it must be manually reset once to restore the connection with the data center, which is considered unqualified. In addition, if DTU supports phone or SMS reset and the test method is effective, it should be considered as qualified. XII) Domain name resolution test (optional test) Test reason: Some application systems use domain names instead of fixed IP addresses, which will increase the link of domain name resolution. Because the domain name resolution service is temporarily invalid, it is necessary to test this project when using domain name resolution. Test method: 1) domain name invalidation simulation, which invalidates dynamic domain names, or sets static domain names as invalid addresses, and sets DTU to find data centers through domain names. When the power is on, DTU will not be able to connect to data center. At this point, restore the domain name pointing, and then observe whether DTU can automatically connect to the data center. The shorter the recovery time, the better. If DTU can't always automatically connect to the data center, it will fail. 2) After the GPRS DTU with the domain name is successfully connected to the data center, perform antenna disassembly test (see item 5) to see if it passes the test. If it is unqualified, it is considered unqualified. 3) After the GPRS DTU with the domain name is successfully connected to the data center, it will be tested after the data center is closed (see item 2) to see if it passes the test. If it fails, it will be regarded as unqualified. If the domain name resolution test fails, it is not recommended to apply this DTU to systems that use domain names to resolve IP addresses of data centers. XIII) Hardware stability test item: 1) High and low temperature test, refer to the general test method for electronic products. Macro-control technology SMS and GPRS modules have undergone high and low temperature aging experiments before leaving the factory. 2) Impact vibration test, refer to the general test method of electronic products. Giant control technology SMS and GPRS module can meet the application of shock vibration occasions, such as air compressor. 3) Pulse group anti-interference test, refer to the general test method of electronic products. The short message and GPRS module of Giant Control Technology passed the 4KV fast burst test of Cyberlab. 2) Electrostatic test, refer to the general test method of electronic products. The short message and GPRS module of Jukong Technology passed the 8KV air discharge test of Cyberlab.