This bit is tied to field buttons as well as an HMI button in the “Main” routine.ĭo note that in RSLogix500, it’s not as simple to give tags a meaningful name. Lastly, the only possible means of de-energizing the fault after it has been triggered is by using the “System Fault Reset” bit. Doing so satisfies the condition mentioned above. Once the B3:50/0 internal boolean is energized, it’s latched in place by the XIC Instruction which is tied to itself. Since the “System Fault Reset” bit is tied to an XIO, it will allow the final bit to energize should the “TEMP HIGH” fault trigger through the I0:0 input on the MicroLogix 1100. This instruction may be replaced by any other which will cause the alarm to energize. The first XIC instruction is the trigger for the alarm. It’s composed of a few basic instructions which we’ve covered in other tutorials. A unique identifier displayed on an HMI screen will allow a skilled engineer to immediately trace the logic on the Programmable Logic Controller and find the root cause of the issue.īuilding an Alarm Rung in Ladder Logix RSLogix500Ī basic alarm rung is shown below. Furthermore, it’s something which programmers often use to troubleshoot the system.
The final outcome will be determined by the programmer. However, the programming of these is absolutely the same.
In other words, there are two types of errors: one which will cause a stop and the other which will not. My approach is quite simple: a fault will cause a stop of a certain process a warning will only be a visual indication for the operator. Whatever the source of the error, the system must be able to capture the occurrence and to act accordingly.Ī common question and debate between PLC programmers is the distinction between the levels of faults & the proper designation of each one.
These conditions can be detected by sensors, be the result of certain operator errors or be programmed in software.
Ultimately, this code is needed to make sure that equipment is brought to a safe condition after a critical failure. This logic allows the programmer to capture any abnormalities, alert the operator of a failure, and prevent system damage. Alarms, Faults, and Warning play a critical role within every PLC Program.