PDM Installation & Configuration: Body Control Functions
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Body Control Functions
04.27
| 00:00 | - In previous course modules, we talked about how PMUs replace the fuses and relays in a conventional automative electrical setup and touched upon how we configure them using chains of basic logical functions to perform more complex actions. |
| 00:14 | In addition to these basic logical operators, most PMU manufacturers include some more advanced functions to let us replace even more parts of a conventional automotive electrical setup. |
| 00:25 | The range of included functions will vary across the range of PMUs in the market so you'll need to read the documentation of the PMU you're considering carefully. |
| 00:34 | For now though, let's have a look at some of the more common functions that are offered. |
| 00:38 | The first of these is a flasher function. |
| 00:41 | This function can be linked to an output and configured with an on and an off time where the input conditions required to enable that output are met, the output will turn on for the specified on time and then off for the specified off time and then repeat that for as long as the input conditions are still met. |
| 01:00 | This function is most commonly used to control the indicator lights of the vehicle. |
| 01:04 | This is great as it replaces a conventional discrete flasher module in the system, further simplifying our wiring and reducing bulk. |
| 01:12 | Pulse is another function that's often available. |
| 01:15 | This is typically used to pulse an output in response to a momentary input condition. |
| 01:20 | The pulse can be configured to have a certain on time and a certain off time. |
| 01:25 | And to repeat a certain number of times. |
| 01:27 | An example of this might be a momentary button on the steering wheel that when pressed once, commands the PMU to flash the headlight quickly 5 times. |
| 01:37 | This could be useful for getting the attention of lapped traffic ahead to let them know that you're going to make a passing maneuver. |
| 01:43 | Another function commonly seen is a timer. |
| 01:46 | These are configured with a set time period and when triggered by an input condition, will remain active until that time period elapses. |
| 01:53 | Timers are a really useful function for configuring a system to respond to a momentary input. |
| 01:59 | A common example of this is an engine start/stop button. |
| 02:02 | When the engine isn't running, so the engine speed is zero and that button is pressed, a timer is triggered. |
| 02:08 | For the sake of this example, let's say that that timer is configured with a period of 5 seconds. |
| 02:13 | We can then configure the PMU to provide power to the starter motor solenoid, cranking the engine, while this timer is active and the engine speed is below a certain value. |
| 02:24 | This will result in a single press of that button cranking the engine until it starts and the engine speed rises above that set value or the timer period of 5 seconds elapses. |
| 02:34 | Toggling is a function implemented on almost all PMUs and once again is a really useful tool for interfacing with momentary inputs. |
| 02:42 | A toggle function does exactly that, it'll toggle an output in response to an input condition. |
| 02:48 | When that input condition is met, if the output is off, it will turn it on and keep it on. |
| 02:53 | The next time that input condition is met, the output is currently on so it will be turned off. |
| 02:59 | Related to the toggle function is the set reset function. |
| 03:03 | This is very similar to a toggling output but instead of responding to a single input condition, it responds to two input conditions. |
| 03:10 | When one of the input conditions is met, the output is turned on, it is set. |
| 03:16 | When the other input condition is met, the output is turned off, it's reset. |
| 03:20 | In the case that both input conditions are met at the same time, the reset function normally takes priority over the set function and that output will be turned off. |
| 03:32 | When we're using toggling or set/reset functions, it's very important that we define the default state of the function. |
| 03:38 | This is the state the function will be in when the PMU is initially powered on. |
| 03:42 | PMUs that use toggling or set/reset functions will either have a setting for this associated with that function configuration or will typically default to that function being off. |
| 03:53 | In this module, we've talked about some more specific functions that are often used for body control applications, being flash, pulse, timers, toggles and set/reset. |
| 04:03 | Although we've discussed a couple of examples of their usage, don't worry if they still seem a little abstract, the reality is that the only way to get comfortable with configuring a PMU and thinking in terms of how to use these functions to achieve your goals is to see them being put to use in the real world. |
| 04:19 | Later in the course, this is exactly what we'll be doing and it's going to make their usage much clearer. |
