SDM-SIO11-Channel Serial Input/Output Module

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1. Which ports on the CR5000 can be used to collect data from serial sensors?

   The CR5000 does not natively support communication with serial sensors; however, SDM-SIO1 modules can be added to collect data from serial sensors.

2. Is there anything special to know about an SDM-SIO1 used with an RS-422 cable?

   The SDM-SIO1 has lower power biasing of its inputs and no internal termination resistors, so it operates in the lowest power state. However, this means it can quite easily detect noise on the RS-422 cable, which can, for instance, be picked up from power leads. A simple solution to this is to add 120R termination resistors at one or both ends of the cable. Although termination resistors are only normally needed on long cable runs, they are also quite effective at reducing noise.

3. How does an SDM-SIO1 act in conjunction with a data logger?

   The SDM-SIO1 acts as a virtual serial terminal to a CRBasic data logger. The data logger’s serial functions can be used to control the device.

4. Is the SDM-SIO1 compatible with Modbus?

   Yes. This feature was added in 2013. Ensure that both the data logger operating system and the SDM-SIO1 firmware are up to date. Using an SDM-SIO1, the data logger can be a Modbus client or server, although the intended and most common use is for client operation. In CRBasic, use theSerialOpen()instruction to configure the SDM-SIO1 interface and theModBusClient()instruction to issue Modbus commands.

5. How can four sensors that produce an RS-232 signal be connected to a CR5000?

   Use four SDM-SIO1s or a single SDM-SIO4.

6. Can the CR800, CR850, CR1000 or CR3000 be used to log an RS-422 output directly, or is an extra unit needed?

   An interface is required. This can be done using an SDM-SIO1, or a third-party RS-422 to RS-232 converter.

7. What are the major differences between the MD485 and the SDM-SIO1?

   The MD485 RS-485 Multidrop Interface is a general communication interface or serial converter. Additionally, the MD485 can be used without a data logger and offers collision avoidance for PakBus communications.

   The SDM-SIO1 Serial Input/Output Module is designed for acquiring data from smart serial sensors, rather than for general communications like data collection or program downloads. The SDM-SIO1 can operate in half- and full-duplex modes, has a smaller form factor, works with RS-422, and can be daisy-chained in quantities of up to 15 on a single three-wire SDM port.

8. Is an SDM-SIO4 necessary to connect a CR1000, CR3000, or CR800-series datalogger with a serial sensor?

   It depends. It is possible to connect serial sensors to a data logger without the use of an SDM-SIO4. However, if the sensors require hardware flow control or true RS-232 voltage levels, an SDM-SIO4 may be needed. The SDM-SIO1 also works with RS-485 signals and is a preferred alternative to the SDM-SIO4.

9. The CR1000/CR3000 wiring panel shows four serial I/O ports on C1 to C8. Do these serial I/O ports provide the same functionality as the SDM-SIO4 module did on a CR10X or CR23X datalogger?

   Not the same, but similar. The SDM-SIO4 provides RS-232 voltage levels; the CR1000 control ports provide 0 to 5 V only. Both usually work with all sensors, and both devices are compatible with RS-232 and TTL logic. The CR1000 is easier to set up and program for serial input. The SDM-SIO1 is a preferred alternative to the SDM-SIO4.

   When compared to the CR10X, the CR1000 can handle strings as a specific data type. It also has more integrated serial interfaces including the following:

   • Four control port pairs—COM1 (C1 TX / C2 RX) through COM4 (C7 TX / C8 RX)
   • RS-232 port
   • CS I/O port for connection to CS I/O peripherals

   The serial I/O capabilities of the CR1000/CR3000 are similar to, and faster than, the SDM-SIO4 capabilities on a CR10X or CR23X. SDM devices are addressable and are connected to a data logger on C1 through C3. Therefore, one benefit of using multiple SDM devices on a CR1000 datalogger is that only three control ports are used.

10. Can binary data be received via the serial terminal of a data logger?

    CR1000, CR3000, CR800-series数据记录仪can be used to collect and process binary data from smart sensors via serial or TCP/IP socket connections. In some cases, a converter or communications peripheral may be required.

    Note:The capabilities mentioned above are not available for the CR200X-series, CR5000, and CR9000X dataloggers.