The SDM-SIO1 module connects to Campbell Scientific dataloggers using the SDM port and communications protocol. It connects to a remote serial device using industry standard hardware that can be set to true RS-232, RS-485 or RS-422 mode. It also supports hardware handshaking.
The SDM-SIO1 expands the number of serial devices that can communicate with a CR800, CR850, CR1000, or CR3000 datalogger. You can attach up to 15 SDM-SIO1 modules to the datalogger. This allows a CR800 or CR850 datalogger to communicate with 17 serial devices and a CR1000 or CR3000 datalogger to communicate with 19 serial devices.
The SDM-SIO1 module connects to the datalogger using the SDM port and communication protocol. The datalogger enables individual modules through an addressing scheme; multiple DMs (in any combination) can be connected to one datalogger. After a module is enabled, it operates independently of the datalogger until additional commands are received or results are transmitted. Total cable length between datalogger and all SDMs cannot exceed 20 feet (6 m).
The SDM-SIO1 accepts up to 2047 bytes of serial data and stores the data in a buffer. The buffer allows remote equipment to transmit large amounts of data without hindering other processes in the datalogger.
The CRBasic program when using the SDM-SIO1 module is similar to the CRBasic program for using the standard datalogger serial port. The only difference in operation between the SDM-SIO1 and a built-in port is that a small delay occurs when transferring data to and from the device via the SDM connection.