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:
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.