Campbell Scientific CR6 CR6 Measurement and Control System - Page 273

Section 7. Installation Syntax: aMv! As an example, the response from the command 5M! is: 500410 where: 5 reports the sensor SDI-12 address. 004 indicates the data will be available in 4 seconds. 10 indicates that 10 values will be available. The command 5M7! elicites a similar response, but the appendage 7 instructs the sensor to return the voltage of the internal battery. aC! Start concurrent measurement. The CR6 requests a measurement, continues program execution, and picks up the requested data on the next pass through the program. A measurement request is then sent again so data are ready on the next scan. The datalogger scan rate should be set such that the resulting skew between time of measurement and time of data collection does not compromise data integrity. This command is new with v. 1.2 of the SDI-12 specification. Syntax: aC! Aborting an SDI-12 Measurement Command A measurement command (M! or C!) is aborted when any other valid command is sent to the sensor. SDI-12 Send Data Command Send data commands are normally issued automatically by the CR6 after the aMv! or aCv! measurement commands. In transparent mode through CR6 terminal commands, you need to issue these commands in series. When in automatic mode, if the expected number of data values are not returned in response to a aD0! command, the datalogger issues aD1!, aD2!, etc., until all data are received. In transparent mode, you must do likewise. The limiting constraint is that the total number of characters that can be returned to a aDv! command is 35 (75 for aCv!). If the number of characters exceed the limit, the remainder of the response are obtained with subsequent aDv! commands wherein v increments with each iteration. aDv! Request data from the sensor. Example Syntax: aD0! 273