CR6 测量控制数据采集器

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1. Why are single-ended measurements used in the ACPower() 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 the ACPower() 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. How many AM16/32B multiplexers can be attached to one AVW200-series module?

   Two multiplexers, each with a maximum of 16 or 32 sensors per multiplexer, can be attached. If temperature measurements are excluded from each sensor, 32 sensors are possible.

3. How many AM16/32B multiplexers can be connected to a data logger at the same time?

   A practical maximum is to connect one multiplexer per every two control terminals on the data logger. Control terminals can be shared between multiplexers to increase the number of connected multiplexers. Sharing terminals, however, requires more complex wiring and programming. Users who would like to connect more than one multiplexer per every two control terminals are advised to contact a sales or support engineer at Campbell Scientific for assistance.

4. CR1000X 和 CR1000 / CR6相比，功耗怎么样?

   When idle, the CR1000, CR6, and CR1000X consume less than 1 mA @ 12Vdc. Similar to the CR6, the CR1000X has a much faster processor that requires more power when up and running. As such, there will be higher current draws during active measurements, serial communications, or when plugged into a PC via USB or Ethernet.

   It may be helpful to think of the CR6 and CR1000X as being built on the same "platform."

5. Does the CR6 use true logic levels for RS-232?

   The CR6 has true RS-232 levels on the RJ45 (CPI), and the data logger can be programmed for RS-232 levels on C1-C2 and C3-C4.

    

6. What is the difference between the microSD cards that Campbell Scientific sells and the cards that are commonly used in the consumer electronics at home?

   Campbell Scientific sells, and embeds in their products, microSD cards that have single-level cell (SLC) memory. In contrast, many electronics retailers sell microSD cards that have multi-level cell (MLC) memory. The difference between these two types of memory is significant.

   • The SLC microSD cards from Campbell Scientific are better suited for industrial and environmental applications where wide operating temperatures, low power consumption, and longevity are very important. Most SLC memory cards are designed with industrial applications in mind and, therefore, often have additional perks such as enhanced protection from ESD (electrostatic discharge) and mechanical damage.
   • The MLC microSD cards commonly available at electronics retailers are less expensive, but they are generally not well suited for the majority of applications in which Campbell Scientific data acquisition products are used.
7. Can the CR6 have simultaneous communications (that is, Ethernet and USB) at the same time between two different computers?

   Yes. The communications tasks run independently of each other, and multiple computers can be connected at the same time. If PakBus is being used to communicate, ensure that the computers are using different PakBus addresses to communicate to the data logger.

8. How can a serial modem be connected to a CR6?

   The serial modem can be connected to a CR6 using any of the following methods:

   • Connect the modem to the RS-232/CPI port on the CR6 using cable pn 31055 (RS-232/CPI RJ45 to DB9 Male DTE).
   • Connect the modem to the RS-232/CPI port on the CR6 using cable pn 31056 (RS-232/CPI RJ45 to DB9 Female DCE).
   • Connect the modem to a C or U terminal pair on the CR6, where the pair has been configured for serial I/O.
   • Connect the modem to the CS I/O port on the CR6 using an SC105.