DRC-FM100-SRM-2 Stop Recorder Module
© 1998 by Chad Conrad and DRC Instruments
Theory of operation
The VDO Fleet Manager 100 on-board computer requires that the vehicle be shut down in order to record the end of a trip leg. This can be undesirable in applications in which the driver leaves the vehicle idling during a service stop, and the service stop is to be recorded. One could simply devise some method of disconnecting the appropriate circuits whenever the vehicle is stopped, but this is problematic: Such a solution results in a loss of valuable idling information for the duration that the FM100 is off, and it may result in too many false stops being recorded.
The FM100-SRM-2 senses an external event, such as the driver's door opening, or a parking brake being set, and then shuts down the FM100 for approximately 24 seconds. It then turns the FM100 back on to record whatever is occurring, such as idling. With the re-arming time set to 18 seconds in the FM100 PC software, the FM100 will always register the end of a trip leg whenever the external event happens. One need only choose an external event that occurs every time a trip leg is to be recorded. We recommend the cab-light switch on the driver's door. The external event can be anything which creates a change from a logical low (ground) condition to a high (+12V) condition, or vice versa. (A signal which is normally low and goes high is known as active high, the reverse is known as active low.) The SRM-2 contains a switch that the installer sets to specify active low or active high.
Determine what kind of trigger signal you will be using. (eg. the door switch, etc. These instructions will assume that you are using the signal from the door light switch.) Is this signal active low or active high? In other words, does the signal go to ground when you wish to record a stop, or does the signal go to +12V?
To determine this, use a properly grounded test lamp. Be sure there is a good bulb in the cab light, and that all switches that operate the lamp are open (ie. the driver door is closed, the lamp is off). With the test light, probe both sides of the door switch until the lamp lights. Now, open the door so that the cab light comes on. If the test lamp stays lit, the signal is active high, and your test lamp is at the point labelled B in figure 1. You will be connecting the SRM-2 to the other side of the switch; call this point A. If the test lamp goes out when the door opens, the signal is active low, and the test lamp is at point A. See figure 2.
Having determined if the signal is active high or active low, open the DRC-FM100-SRM-2 and set the switch to H or L, for active high or active low.
Determine if the isolating diode is to be installed. (See below.)
Using the door light switch, you will trigger a trip record every time the door is opened. In some vehicles, there are two switches that share the same circuit (eg. a switch in the cab and the switch on the door). In these circumstances, a trip record may be triggered every time the driver uses the auxiliary switch to turn the light on. Note that in some vehicles the switches are isolated from each other so that this does not occur. You may wish to use a logic probe at point A (figures 1 and 2) to determine if the auxiliary switch affects point A. If it does, and if this behaviour is not desired, you must install the provided isolating diode in series (ie. you will be cutting the wire) with the door switch, as indicated in figures 3 and 4. If you will not be using the isolating diode, then omit it (do not cut the wire). The bent lead of the device is the negative lead (see figures 3 and 4).
Install the FM100-SRM-2 as indicated in figures 3 and 4, according to the appropriate situation (active high or low). Be sure to connect the ground and constant power lines before any other connections.
In the FM100 software, set the arming time for the vehicle to 18 seconds. The FM100 must "log out" the current driver and rearm itself for a trip record to be generated. See figure 5. (The FM100-SRM-2 is set to turn the FM100 "off" for about 24 seconds.)
Instruct the client/driver: If maintaining the correct driver ID is important to the client, instruct them that they must leave the blue key in the port whenever the vehicle is running so that the FM100 will automatically log the driver back in after each interruption. Alternatively, if the FM100 is set to give an alarm when attempting to start the vehicle without a blue key, then the driver can reintroduce his key upon returning to the vehicle every time this alarm sounds.
Size: 33mm × 89mm × 64mm
Copyright © 1997, 1998 Chad Conrad and DRC Instruments ALL
Copyright © 1997, 1998 Chad Conrad and DRC Instruments ALL RIGHTS RESERVED