Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 207

Section 7. Installation SerialOutBlock()1,3 • Binary • Can run in pipeline mode inside the digital measurement task (along with SDM instructions) if the COMPort parameter is set to a constant argument such as COM1 or COM2 , and the number of bytes is also entered as constant. SerialOut() • Handy for ASCII command and a known response, e.g., Hayes-modem commands. • Returns 0 if not open, else the number of bytes sent SerialInRecord()2 • Can run in pipeline mode inside the digital measurement task (along with SDM instructions) if the COMPort parameter is set to a constant argument such as COM1 or COM2 , and the number of bytes is also entered as a constant. • Simplifies synchronization with one way. • Simplifies working with protocols that send a "record" of data with known start and/or end characters, or a fixed number of records in response to a poll command. • If a start and end word is not present, then a time gap is the only remaining separator of records. Using COM1 or COM2 coincidentally detects a time gap of >100 bits if the records are less than 256 bytes. • Buffer size margin (one extra record + one byte). 1Processing instructions 2Measurement instruction in the pipeline mode 3 Measurement instruction if expression evaluates to a constant 7.8.8.5.2 Input Programming Basics Applications with the purpose of receiving data from another device usually include the following procedures. Other procedures may be required depending on the application. 1. Know what the sensor supports and exactly what the data are. Most sensors work well with TTL voltage levels and RS-232 logic. Some things to consider: • Become thoroughly familiar with the data to be captured. • Can the sensor be polled? • Does the sensor send data on its own schedule? • Are there markers at the beginning or end of data? Markers are very useful for identifying a variable length record. • Does the record have a delimiter character, e.g. ",", spaces, or tabs? These delimiters are useful for parsing the record into usable numbers. 207