Campbell Scientific CR10 CR10 Measurement and Control - Page 38

SECTION 1. FUNCTIONAL MODES Subroutines 97 and 98 have the unique capability of being executed when a port goes high (ports 7 and 8 respectively). Either subroutine will interrupt Tables 1 and 2 (Section 1.1.3) when the appropriate port goes high. PorlT cannot wake the processor, subroutine 97 will be executed at the next 1/8 second interval after the port'goes high. Port 8 will wake the processor within a few microseconds. The port triggers on the rising edge (i.e., when it goes from low to high). lf the port stays high the subroutine is not called again. 1.1.3 TABLE PRIORITY/INTERRUPTS Table 1 execution has priority over Table 2. lf Table 2 is being executed when it is time to execute Table 1, Table 2 will be interrupted. After Table 1 processing is completed, Table 2 processing resumes at the interruption point. lf the execution interval of Table 2 coincides with Table 1, Table 1 is executed first, then Table 2. Interrupts by Table 1 are not allowed in the middle of an instruction or while output to Final Storage is in process (flag 0 is set high). The interrupt occurs as soon as the instruction is completed or flag 0 is set low. Special subroutines 97 and 98, initiated by a port going high (Section 1.1.2), can interrupt either Table 1 or 2 or can occur when neither is being executed. These subroutines can interrupt a table while the Output Flag is set. When the port activating 97 or 98 goes high during the execution of a table, the instruction being executed is completed before the subroutine is run (i.e., as if the subroutine was called by the next instruction). The priority is 98, 97, Table 1, Table 2. lf both 97 and 98 are pending (ports go high at the same time or both go high during the execution of the same instruction in one of the tables), 98 will be executed first. lf 97 or 98 has not interrupted a table then neither table can interrupt it. 97 and 98 cannot interrupt each other. However, when 97 or 98 interrupts a table, it is as if the subroutine were in the table (e.9., if 98 interrupts Table 2, either Table 1 or 97 can interrupt it). While 97 or 98 is being executed as a result of the respective port going high, that port interrupt is disabled (i.e., the subroutine must be completed before the port going high will have any effect). 1.1.4 COMPILING A PROGRAM When a program is first entered, or if any changes are made in the *1 , *2, *3, *A, or *C Modes, the program must be compiled before it starts running. The compile function checks for programming errors and optimizes program information for use during program execution. lf errors are detected, the appropriate error codes are indicated on the display (Section 8.10). The compile function is executed when the *0 saving , *6, or *B Modes a program listing are entered and in the *D Mode. prior The to compile function is only executed after a program change has been made and any subsequent use of any of these modes will return to the mode without recompiling. When the *0, *8, or *D Mode is used to compile all output ports and flags are set low, the timer is reset, and data values contained in lnput and Intermediate Storage are reset to zero. When the *6 Mode is used to compile data values contained in Input Storage, the state of flags, control ports, and the timer (lnstruction 26) are unaltered. Compiling always zeros Intermediate Storage. 1.2 SETTING AND DISPLAYING THE CLOCK - *5 MODE The *5 Mode is used to display time or change the year, day or time. When "*5" is entered, the time is displayed and updated approximately once a second or longer depending on the rate and degree of data collection and processing taking place. The sequence of time parameters displayed in the *5 Mode is given in Table 1.2-1. To set the year, day or time, enter the *5 Mode and advance to display the appropriate value. Key in the desired number and enter the value by keying "A". When a new value for hours and minutes is entered, the seconds are set lo zero and current time is again displayed. To exit the *5 Mode, key "*" and the mode you wish to enter. When the time is changed, a partial recompile is done automatically to synchronize the program with realtime. Changing time will also affect the output and execution intervals during which time is changed. Because time can only be set with a 1 second resolution, execution intervals of 1 second or less remain constant while time is reset. Averaged values willstill be accurate, 1-2