In some cases you may need to flash a bit in your PLC program. Let’s say that you have an HMI that is not capable of flashing an alarm notification. In that case, you may use the PLC program and one of a number of ways to flash a bit. You can then use that bit on the HMI to indicate a flashing alarm symbol. There are many reasons why you may want to use flashing bits. Let’s open up this lesson and see how you can do that.
In the previous lesson we talked about the different ways to generate timing pulses or flashing bits within your PLC program. Also, in other lessons, some time ago, we discussed how to generate pulses using timers. In this lesson, we are going to recap how to create these pulses and work with the...
In this lesson, we are going to discuss how to handle alarming. Visual alarm indicators may be lights on the plant floor or alarm symbols on an HMI screen and as common industry standard, an indicator should flash when an alarm occurs but only until acknowledged. After acknowledgement, the indica...
In the previous lesson we began writing some code that would post and acknowledge alarms per industry standard. As you know, we ran into a little problem with the code clearing the alarm after acknowledgement but it would not re-post the alarm in constant mode. In this lesson, we are going to tro...
27 Comments