MoTeC M1 Software Tutorial: Engine Outputs
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Engine Outputs
08.40
| 00:00 | One aspect of the M1 that differs significantly from MoTeC’s hundred series ECUs is the way the M1 deals with outputs. |
| 00:09 | The M1 is quite defined as to what we can and can’t do with a particular output, and this can have the ECU feel quite restricted if you have just moved to the platform. |
| 00:20 | The first worksheet we will deal with is the ‘Engine Outputs’ sheet and there isn’t a lot of work to do here. |
| 00:27 | Obviously what you will need to configure will depend on your particular installation, but the outputs here include cooling fans, the fuel pump control and a warning light. |
| 00:39 | We also have the option to test the output operation if we expand out the ‘Engine’ tab of the tree. |
| 00:45 | This just repeats the same test functionality we have already looked at previously. |
| 00:51 | If we expand out the ‘Cooling Fan’ output, you can see that we have the ability to control two fans. |
| 00:58 | The first step with setting up a fan is to enable the output by using the drop down box under the ‘Mode’ parameter. |
| 01:06 | Next we are going to move down and you can see that we have a ‘Frequency’ setting. |
| 01:11 | This can be used to define the operating frequency for a pulse width modulated fan or you can leave it set to zero for a switched output. |
| 01:20 | If we move down, you can now assign an output resource to this particular fan. |
| 01:27 | The actual operation of the cooling fan is defined by the enable conditions. |
| 01:33 | In this case we first of all have a coolant temperature enable and a hysteresis. |
| 01:39 | This means that any time the coolant temperature exceeds the enable temperature, the fan will operate and will continue to do so until the temperature drops by the hysteresis value. |
| 01:51 | If we wish to use this particular cooling fan when the air conditioning is active, we can enable this mode here. |
| 01:58 | This will run the cooling fan when the air conditioning clutch state is ‘On’. |
| 02:03 | The M1 also gives us the ability to control the fan operation based on vehicle speed. |
| 02:10 | This function works by disabling the fan operation if the vehicle speed exceeds the threshold value here, and the fan operation won’t resume until the vehicle speed drops below the threshold by the hysteresis value. |
| 02:25 | If you are using a pulse width modulated fan output, you can adjust the duty cycle of the fan in the ‘Air Conditioner’ and ‘Coolant Temperature’ tables. |
| 02:34 | The ECU will operate the gan at whichever is the higher duty cycle from these two tables. |
| 02:41 | Lastly we can also monitor the current voltage on the output pin of the ECU here. |
| 02:47 | If you have dual fans, the settings for ‘Fan 2’ replicate the ones we have just looked at. |
| 02:54 | If we move down the tree, we now have a branch labelled ‘Engine’ and expanding this out gives us the ‘Test Output’ functionality we have already looked at elsewhere. |
| 03:05 | The next output we need to setup is the fuel pump drive. |
| 03:09 | It’s important to point out that the ECU can’t directly operate the fuel pump due to the high level of current draw. |
| 03:17 | Normally we would use the fuel pump output to control a relay to switch the fuel pump on, or if a PDM is fitted, the M1 will output the fuel pump state to the PDM to allow control this way. |
| 03:30 | We can start setting up this output by setting the ‘Mode’ to ‘Enable’ here from the drop down menu. |
| 03:37 | We then have two settings for ‘Hold’ and ‘Prime’. |
| 03:41 | The Hold function will delay the fuel pump switching off after the ignition is switched off by the entered value. |
| 03:48 | If you don’t want to use this function, entering zero will disable it. |
| 03:53 | The prime function is used to build pressure in the fuel system when the ECU is switched on prior to starting and a value of 2-3 seconds is pretty typical. |
| 04:04 | Now we can configure the how the ECU will switch the fuel pump drive. |
| 04:08 | We have the option of ‘High Side’ which will switch to twelve volts, or ‘Low Side’ which will switch to ground. |
| 04:16 | This will depend how the output relay is wired. |
| 04:20 | If you want to use a High Side output, this is only available when a half bridge output is selected. |
| 04:27 | Now we can move down and allocate the fuel pump to an unused resource. |
| 04:33 | Next we can also configure a diagnostic for the fuel pump output to indicate a problem with the output. |
| 04:40 | You can also monitor the instantaneous voltage on the fuel pump pin here. |
| 04:46 | The last option in this worksheet is to configure a Warning Light if desired. |
| 04:51 | This is simply an output that would normally be used to trigger a driver warning light if any of the warning conditions are met. |
| 04:59 | The warning light is controlled by the ‘State’ and this is requested by the M1’s warning system. |
| 05:06 | Configuring the warning light simply requires an unused resource to be configured. |
| 05:12 | If we move on to the ‘Auxiliary Outputs’ worksheet, we have four separate outputs that we can configure to control auxiliary outputs. |
| 05:20 | Each of the four outputs offers different strategies for controlling the output, so it’s important to understand how each works so you can choose the correct output for whatever you are trying to control. |
| 05:32 | Again there is a limited amount of flexibility in what we can do with these outputs. |
| 05:37 | Let’s look at Output 1 for an example and we will expand this out to look at all of the settings. |
| 05:44 | Output 1 is actually the most flexible as this is the only output that offers the ability to actually trim or compensate the fuel and ignition timing based on the output. |
| 05:54 | This is useful if you are using the output to control anything that is likely to effect the engine’s volumetric efficiency or ignition and fuel requirements. |
| 06:03 | This might include a function such as a variable inlet runner mechanism or water injection for example. |
| 06:11 | The operation of this particular output is a little complex and will depend on a few different settings so let’s go through them now. |
| 06:19 | We will start with the ‘Polarity’. |
| 06:22 | If this is set as ‘Normal, the output duty cycle is equal to the requested duty cycle in the table. |
| 06:29 | If it is set to ‘Inverted’, the output duty is the inverse of the requested duty. |
| 06:36 | Next we have a duty cycle table which is a 3D table of RPM vs Throttle Position. |
| 06:44 | We use this table to request the output duty cycle we want. |
| 06:47 | When the activation points are exceeded. If you are going to use a half bridge output, using numbers between 0 and -100 will result in a high side output or one that drives to 12 volts. |
| 07:02 | Once the duty cycle table is filled in, we can choose where we want the output to activate. |
| 07:07 | This particular output is activated based on manifold pressure, and this must be between the minimum and maximum values for the output to be active. |
| 07:16 | A hysteresis value is included to prevent the output cycling rapidly at the activation pressure. |
| 07:23 | A parameter called Race Time is also included which allows the activation to be controlled. |
| 07:29 | We will look at Race Time function in detail a little further through the course. |
| 07:35 | Next we have the output frequency which can be set to zero for a switched output, or the desired frequency for a pulse width modulated output. |
| 07:45 | We can also assign the output resource as usual from the drop down menu. |
| 07:50 | Lastly we have three compensations that we can use to control the ignition, fuel volume and aim mixture based on the outputs duty cycle. |
| 08:00 | If you want to use any of these compensations, we can open the axis setup and configure a table based on output duty cycle as required. |
| 08:10 | It’s worth mentioning that the M1 will always use the richest target from any of the Mixture Aim tables, so generally if we don’t want a particular Mixture Aim table to influence the requested mixture, we leave this set to 2.0 as you can see here. |
| 08:27 | The remaining Outputs can be configured in the same basic way. |
| 08:31 | There is no right or wrong way to set up these outputs, and how you use them and which ones you use will depend on what you want to operate and how you want it to switch. |
