CR1000Measurement and Control Datalogger

展开全部Collapse All

1. Why are single-ended measurements used in theACPower()instruction in CRBasic when the outputs of the potential transformer and current transformer are inherently differential?

   The potential transformer and the current transformer provide differential outputs that have galvanic isolation from the voltage and current in the circuit they are measuring. However, there is no need to run the outputs of these transformers into differential inputs of the data logger and unnecessarily consume additional data logger channels. We conducted extensive testing for noise immunity, for inaccuracies from ground loops, and more before concluding that single-ended measurements in theACPower()instruction have the same performance as differential measurements would provide. Please note that as a result of the galvanic isolation of the potential transformer and current transformer, the data logger ground is NOT connected to the ground of the circuit they are measuring.

   Said differently, you can connect differential outputs of a sensor to single-ended inputs of the data logger. However, doing so creates the possibility of poor common-mode noise rejection in the data logger and the possibility of introducing inaccuracies from ground loops between the sensor and the data logger. Note that in this application, the transformer isolation of the potential transformer and the current transformer eliminates these concerns.

   Simply connect one of the potential transformer secondary wires and one of the current transformer secondary wires to the data logger ground. Which wire in either case makes a difference, as the phase information allows the measurement of power flowing in either direction. If you measure negative real power when it should be positive, then reverse the secondary wires of the potential transformer where they connect to the data logger. Alternatively, you can reverse the secondary wires on the current transformer, but don't reverse both pairs of wires.

2. Does a server certificate affect the communication speed of a CR1000?

   In OS 24, any delay in the CR1000 communication while reading a server certificate is because the data logger has to work its way through the certificate and set up the encryption to continue with secured communication. This speed depends on the processing power of the data logger.

3. Can a CR5000 and a CR1000 be networked so that the data from both can be downloaded over a single cellular digital modem?

   是的。Create a multidrop network with an MD485 between the CR5000, the CR1000, and the digital modem. See the “Digital Cellular Modem to MD485 Network” appendix item in theMD485 instruction manual。

4. Do the CR800-series, CR1000, and CR3000 dataloggers have 50 Hz versions?

   50 Hz rejection is available for analog voltage measurements by setting the Integration parameter.

5. CR1000通过串行连接将CR1000直接连接为CR3000吗？

   是的。The CR1000 could be set up as a SDI-12 sensor using theSDI12SensorSetup()instruction. Alternatively, the CR1000 could be set up to perform serial communications with the CR3000 by connecting a COM1─COM4 port pair and ground from one data logger to a COM1─COM4 port pair and ground on the other data logger. The COM1─COM4 port lines need to cross RX to TX and vice versa.

6. 可以使用COM320和NL120在单个CR1000上运行双通信模式？

   是的。通过将NL120配置为CSDC设备，NL120和COM320都可以共享相同的CS I / O端口。CR1000和CR3000能够多线程，因此NL120和COM320可以并联运行。有关更多信息，请参阅NL120 Ethernet Module Instruction Manual。

7. 在哪里可以找到处理器使用信息？

   对于CR1000 Datalogger，该Statustable, accessed from the CR1000KD orLoggerNet(version 4)Connectscreen,Station Statusbutton, has some statistics that may be useful. Refer to “ProcessTime,” “MaxProcTime,” “MeasureTime,” and “MeasureOps”在附录B中CR1000操作员手册。

8. Can an NL120 be used to connect multiple CR1000 or CR3000 dataloggers to the Internet?

   No. The NL120 is used for one device only.

9. How effective are pass-code lockouts for CRBasic PakBus data loggers?

   Pass-code lockouts (historically known as security codes) are the oldest method of securing a Campbell Scientific data logger. This method provides a level of security, mainly for PakBus communications. However, someone with physical access to a data logger or telecommunications hardware may be able to overcome the five-digit pass-code lockouts. To further secure PakBus communications, use the PakBus Encryption Key and PakBus/TCP password.

10. How many tables can be defined for the CR1000?

    The number of data tables that can be user-defined is more than 250.