Handling a complex world. How to multiplex an FM200 analogue input Introduction This document describes how to configure an FM200 analogue/digital input to monitor 2 digital sources. This document is intended for readers with a detailed understanding of the functionality and terminology of the VDO Fleet Manager system as well as an understanding of electronics. Hardware requirements The only additional hardware required is two resistors, the first one being a 47 KO 5% 0.2W and the second one being a 22 KO 5% 0.25W resistor. You may use more accurate resistors or resistors with a higher power rating. Installation notes It is important to note that the combination of these two resistors will result in 4 possible combinations of voltage readings on the analogue/digital input. This solution will be most accurate when connected to low impedance sources such as solenoids or relay coils where a high voltage swing will occur. Hardware installation Refer to the wiring diagram in Figure 1. Connect the 47KO resistor in series (in-line) with your first digital input (referred to in this document as I1A) to any one of the four FM200 analogue/digital inputs (I1 through I4). Connect the 22KO resistor in series (in-line) with your second digital input (referred to in this document as I1B) to the same FM200 analogue/digital input. It is important that the second digital source is connected on the FM200 side of the 47KO resistor. The two lines with their series resistors will be in parallel with one another. Figure 1 - Wiring Diagram Connecting to an active low or active high source
An active low source is a source that is considered active when it is low. The line/point being measured is low when the relay, solenoid or power take-off is energized or engaged. Figure 2 depicts an example of this. When the switch is closed, the load will be engaged and the analogue/digital line will be pulled low through the 47KO resistor and the switch. An active high source is a source that is considered active when it is high. An example is illustrated in Figure 3 where the switch will pull the analogue line high through the 47KO resistor. Figure 2 - Active Low Source Figure 3 - Active High Source Table 1 shows the four options that can be derived from using the two resistors on an analogue input in a 12V, 24V or 36V installation. It is critical that you identify in which state the digital source will be considered active. The table is based on the assumption that you use the documented resistor values (47KO & 22KO). The table will allow for a 5% tolerance on the two resistors and will accommodate the voltage difference between a charging and discharging circuit. Table 1 Digital lines 11-13.6V Voltage range 22V 28V Voltage range 32V 38V Voltage range I1A Low I1B 0V 0V - 0.8V 0V 0V - 1.7V 0V 0V - 2.5V Low I1A Low I1B 3.6V 2.7V- 4.4V 7.1V 4.4V- 8.8V 10.6V 7.8V- 13.1V High I1A High I1B 1.7V 0.8V- 2.7V 3.3V 1.7V- 4.4V 4.9V 2.5V- 7.8V Low I1A Hi I1B High 5.2V > 4.4V 10.4V > 8.8V 15.6V > 13.1V Date : 19 December 2002 Page 2 of 10
The Voltage range columns list the voltage ranges to be used in conjunction with the voltage level for a given combination. For example if I1A is high and I1B is low the voltage is 1,7V. This enables you to define an event using voltage values of > than 0.8V and < that 2.7V. This range is wide enough to cover 5% resistors and a supply voltage with a swing of +11V to +13.6V Important: If your digital source does not have a full voltage swing of 0V to 12V but only changes from a 3V to 9V then you need to make adjustments to the voltage levels used. It is best to only multiplex digital sources that change from one voltage rail to the other (0V to 12V) or more. Software configuration Introduction This section of the document should be read in conjunction with the documents entitled Parameter and Event Definition in the Fleet Manager system, and How to Create Custom Events which provides a more detailed explanation of unit configuration. How to define an event The following steps define the procedure to be followed to create Multiplexed input line events. These events will detect and record events where two digital sources are connected to one analogue input. The first step is to create a new device The first step in creating this new event is to create a Multiplexed line I1 device, which will be used in the definition of the new Emergency siren event. To access the Event Definitions dialog, click the Edit menu, and then click Event Definitions. Click the Devices tab. Click the Add button. The Add Device Wizard will be displayed. Date : 19 December 2002 Page 3 of 10
Enter a description for the new device. Make the description meaningful for example Multiplexed line I1 if you are using the I1 input of the FM200 unit. It is important to note that because two or more different events will use this device, a generic name will be more meaningful. Click Next. Select Create a new device and click Next. Select Standard analog sender and click Next. Date : 19 December 2002 Page 4 of 10
Select Create a new parameter and click Next. Enter a suitable description for the parameter. It makes sense to give the parameter the same description as the device. Enter V for Volts as the units for the parameter. Click next. Click Finish. Date : 19 December 2002 Page 5 of 10
Click the Calibration tab. Enter a value of 0V with a corresponding value of 0mV in the first pair of calibration fields. Enter a value of 1V with a corresponding value of 1052mV in the second pair of calibration fields. Click Ok. The second step is to define your event Click the Event Configuration tab. A list of Events currently defined for your organisation will be displayed Click Add to create the new event. Date : 19 December 2002 Page 6 of 10
In the description field describe your event, for example Emergency siren on. To set up the event, you must understand the vehicle installation before making your selection. Is this device on the 47KO line (I1A) or the 22KO line (I1B) and is this a 12V, 24V or 36V vehicle? Will this line be high or low when the alarm is active? For an active low source on 47KO line (I1A), the values from Table 1 in the I1A Low rows and in the correct operating voltage columns should be used. Make use of brackets to avoid confusion if necessary. Remember that according to the rules of BODMAS, And is evaluated before Or so brackets are not required in the following example: For an active high source on the 47KO line (I1A) the values from Table 1 in the two I1A High rows and in the correct operating voltage columns should be used. There are two voltage values (rows) for each possible combination in the table. To enable you to specify the limits or voltage range when you configure the events, we have included a column with these ranges completed in Table 1 called Voltage range. For the active high on the 47KO line (I1A) the two settings are 1.7V and 5.2V. For the range 0.8 to 2.7V and higher, 4.4V will be used in your event definitions. Date : 19 December 2002 Page 7 of 10
Click the Record tab. This tab allows you to specify a time delay for the recording of the event, as well as the event type, and whether or not you would like a specific value recorded when the event occurs. When setting up the recording time it is important that you set the time delay to at least two seconds. This will allow for the voltage input level to change from a high to a low without triggering events that are referenced to voltages between those two. In the Event Type frame, specify whether only occurrences of the event should be recorded (Notification only), whether the start and end times of each occurrence should be recorded, or whether a summary (the number of occurrences and total duration) should be recorded. These options affect the amount of memory used within the unit. The events on the 22KO line can be defined in the same way, by following the steps in sections 2.1 to 2.5. You will also make use of the same parameter when defining these events (Multiplexed line I1). Should you wish to multiplex more than one analogue input, please follow steps 2.1 through 2.7 to configure each multiplexed input. You will of course use a different parameter for each input, for example if you are multiplexing I3, you could use a parameter named Multiplexed line I3. This parameter will be used to define both of the new events required to monitor the sources connected to the I3 input. Important: The voltage setting in the table is for a 0V low and a 11-13.6V high or 0V low and 22-28V high" or 0V low and 32-38V high. If the device on one of your lines has different voltage levels then you need to recalculate the values for your event settings. The third step is adding another input to your vehicle. Select the appropriate vehicle in the list view. Double-click on the vehicle entry to display the Vehicle Properties dialog. Date : 19 December 2002 Page 8 of 10
Select the Device tab. Double click on the input line that the two digital sources will be or have been connected to. Select the Multiplexed line I1 from the Devices drop down box and click Ok. Your vehicle is now set up to monitor two digital sources connected to the I1 analogue input. Date : 19 December 2002 Page 9 of 10
Congratulations! You have defined a multiplexed digital input with its corresponding events and enabled them to be monitored by the FM200 unit. Remember: You must upload the new configuration into the FM200 unit. Date : 19 December 2002 Page 10 of 10