ABB Robot Variable Logical Cross Connections

1. Introduction
   The purpose of Logical Cross Connections is to check and influence the combination of digital I/O signals (DO, DI) or grouped I/O signals (GO, GI). This can be used to verify or control process equipment outside the robot. This function is equivalent to a simple PLC.
   If the I/O system is allowed to process logical operations with I/O signals, many RAPID codes can be avoided. LogicalCrossConnections can replace the process “read I/O signal value, calculate new value, and write value to I/O signal”.

Logical Cross Connections in ABB robots are crucial for establishing relationships between different signals and variables. They enable seamless communication and coordination within the robot system. These connections allow for conditional operations, data transfer, and synchronization of various components. By defining these logical links, users can customize the robot’s behavior, making it more adaptable and efficient for specific tasks.

Here are some application examples:

1. When any of the three input signals is set to 1, the system interrupts the program execution process.
2. If both input signals are set to 1, then set an output signal to 1.
   The purpose of Logical Cross Connections is to define the dependency between an I/O signal and other I/O signals. More complex dependencies can be configured using logical operators AND and OR and inverted signal values. If an I/O signal consists of a corresponding logical expression (execution I/O signal) and an I/O signal resulting from the expression (synthetic I/O signal), then the signal can be a digital I/O signal (DO, DI) or a grouped I/O signal (GO, GI).
   With LogicalCrossConnections, you can build a logical expression with up to 5 execution I/O signals, logical operations AND and OR, and inverted signal values.
3. Limitations
4. Order of evaluation
   If more than two execution I/O signals are used in a cross connection, they are evaluated from left to right. This means that the operation between Actor 1 and Actor 2 is evaluated first, and then the result is used in the operation with Actor 3. If all operators in a cross connection are of the same type (only AND or only OR), the order of evaluation does not matter. However, if AND and OR operators are mixed without considering the order of evaluation, unexpected results may occur. 2. Maximum number of execution I/O signals
   A cross connection may not have more than five execution I/O signals. If more I/O signals are required, use more cross connections.
5. Maximum number of cross connections
   The robot system handles up to 300 cross connections.
6. Maximum depth
   The maximum allowed depth of cross connection evaluation is 20. The result of one cross connection can be used as an actuator for another cross connection, and the result of the latter can be used as an actuator for the next cross connection in turn. However, the depth of such a dependent cross connection chain cannot exceed 20 steps.
7. Do not create loops
   Cross connections must not come from closed chains, otherwise it will lead to infinite evaluation and oscillation. Closed chains occur when cross connections are related to each other and make the cross connection chain form a loop.
8. Do not have the same result more than once
   Ambiguous composite I/O signals must not be used, otherwise the relevant results will depend on the evaluation order (this order cannot be controlled). Ambiguous composite I/O signals occur when several cross connections result in the same I/O signal.
9. Overlapping Device Mappings
   For a composite I/O signal in a cross-connect, its device mapping must not overlap with any reverse-execution I/O signal defined in the cross-connect. Using I/O signals with overlapping device mappings in a cross-connect will result in an infinite signal setting loop.