Topic: DMD0186
Instruction Set for Do-more CPUs
Do-more Designer uses the differently colored
triangles in the upper left corner (called class designators) to draw attention to instructions that require
special consideration when using them in a ladder logic diagram.
Fully Asynchronous Instructions are dependent on a shared device (like the Ethernet Port or a serial port), which means that the instruction may have to wait on the availability of the shared resource before it can run.
Multi-scan Instructions will take two or more PLC scans to complete, typically because the instruction has Termination Logic that needs to run on the scan immediately after the instruction completes.
Skipping Instructions will alter the normal execution order by moving the execution pointer forward or backward in the ladder logic diagram, for example, the GOTO instruction can skip sections of ladder logic by moving forward, or repeat section of ladder logic by skipping backwards.
Yielding Instructions can temporarily suspend its processing on the current scan and resume processing at that same point on the subsequent scan. When using any of the looping instruction (for / next, do / while ...) this allows you to specify how much time to allow on each scan for the loop to run.
Yielding / Skipping Instructions can alter the normal execution order by moving the execution pointer forward or backward in the ladder logic diagram, AND can temporarily suspend its processing on the current scan and resume processing at that point on the subsequent scan.
Some of the Instructions have additional logic that is used to reset the internal state of the instructions when they are disabled so that they will run properly when they are next enabled. This logic is called Termination Logic.
Has Termination Logic means these instructions have additional actions that are performed when they stop executing.
These instructions have termination logic but that logic in NOT performed if the instruction is in an Interrupt Service Routine.
Some of the instructions cannot be placed inside certain types of code-blocks.
These instruction can only be placed in a Program code-block.
These instructions can not be placed in an Interrupt Service Routine.
These instructions can not be placed in a Subroutine.
These instructions can be placed in a Subroutine if the input leg is configured as power flow enabled.
Some of the instructions require optional hardware resources, such as the on-board Ethernet port or a CTRIO module.
On-board Ethernet Port means these instruction can only be used on Do-more CPUs with an on-board Ethernet port.
Requires the addition of a CTRIO or CTRIO2 module.
Requires the addition of a CTRIO2 module - these are NOT for use with the CTRIO module.
Requires High-Speed I/O discrete input and / or output points - for example the on-board 24 Volt DC inputs and outputs of the BRX PLCs.
Requires the use of on-board discrete inputs and outputs of the BRX PLCs, or a BX-HSIO1, BX-HSIO2, or BX-HSIO4 module.
