Digital I/O Digital I/O Omron Adept controllers can communicate in a digital fashion with external devices using the Digital I/O capability. Digital input reads the status of a signal controlled by user-installed equipment. A typical digital input operation is to wait for a microswitch on a workcell conveyor to close, indicating that an assembly is in the proper place. The WAIT instruction and SIG function are used to halt program execution until a digital input channel signal achieves a specified state. The program line: WAIT SIG(1001) halts program execution until a switching device attached to digital input channel 1001 is closed.
If signal 1002 is a sensor indicating a part feeder is empty, the code: IF SIG(1002) THEN CALL service.feeder() END checks the sensor state and calls a routine to service the feeder if the sensor is on. The SIGNAL instruction is used for digital output. In the above example, the conveyor belt may need to be stopped after digital input signal 1001 signals that a part is in place. The instruction: SIGNAL(-33) turns off digital output signal 33, causing the conveyor belt connected to signal 33 to stop. When processing on the part is finished and the part needs to be moved out of the work area, the instruction: SIGNAL(33) turns the conveyor belt back on.
The digital I/O channels must be installed before they can be accessed by the SIG function or SIGNAL instruction. The SIG.INS function returns an indication of whether a given signal number is available. The code line: IF SIG.INS(33) THEN can be used to ensure that a digital signal is available before you attempt to access it. The monitor command IO displays the status of all digital I/O channels. For details on installing digital I/O hardware, see the SmartController EX User's Guide . Digital output channels are numbered from 1 to 512. Input channels are in the range 1001 to 1512. Multiple signals can be turned ON or OFF with a single instruction.
SIGNAL(33),(-34),(35) or SIGNAL(-33),(34),(-35) eV+Language User's Guide, v2.x, 18318-000 Rev A Page 137