The following illustrates the recommended power connections for using a vehicle electrical system as the eDAQXR EXRCPU or eDAQXR-lite EXRLCPU system power source. The included diagrams are not intended to be complete or detailed instructions.
CAUTION
Connection to the positive power terminal without proper grounding may result in damage to the eDAQXR or eDAQXR-lite system.
NOTE
When using additional cable length to make the power connections, select an appropriate gauge wire to carry sufficient current (≥10 amps).
Vehicle Frame Ground applications
The following diagram illustrates a method of powering an eDAQXR (EXRCPU) or eDAQXR-lite (EXRLCPU) system with a direct connection to a vehicle battery that has a permanent ground connection to the vehicle chassis (Frame Ground).
CAUTION
When connected as shown, the EXRCPU/EXRLCPU is still frame grounded if battery negative (-) is removed. For all electronics, removing battery (-) while the unit has applied voltage can cause unpredictable effects and possibly damage. It is highly recommended to always remove V+ first, no matter what the configuration. Due to the super caps backup system, transducer power can still exist without a battery (-) connected.
Careful consideration must be given to the grounding scheme when the EXRCPU is used with legacy 16-channels layers. Digital Ground, V- and stud are all connected together by the legacy layers.
NOTE
When main power is removed, super capacitors in the eDAQXR or eDAQXR-lite become engaged to allow the unit time to save data and properly shut down. The super caps will need several seconds to recharge between cycles. If power keeps getting cycled on and off these super caps may not have enough time to charge up. Data may be affected if the super caps became prematurely depleted of energy. If the eDAQXR or eDAQXR-lite stays permanently connected to Battery power and the remote switch is used to shut off the unit, the super caps do not engage during shutdown.
Facts about the remote switch:
The remote switch is pulled up to Vehicle power (V+) through a 100k Ohm resistor inside the EXRCPU/EXRLCPU. The return is a digital ground. The connections are designed to be a dry contact between the remote switch lines. This means that only isolated switch contacts can be used with the "Remote Switch Wires". Examples would be would be a toggle switch or a mechanical relay. For an electronic solution opto coupler with an open collector output can be made to work. The remote switch return (Pin 14) should never be tied to Frame Ground (V-). When using the digital I/O pins 10 and 13 should never be tied to Frame Ground (V-).
Power connector (input D-Sub 15-pin male connector) pin assignments
Pin | Function | Pin | Function | |
---|---|---|---|---|
1 | V+ (Power) | 9 | V+ (Power) | |
2 | V+ (Power) | 10* | Input 1 (Digital Ground) | |
3 | Input 1 | 11* | Input 2 (Digital Ground) | |
4 | Input 2 | 12 | Output 1 | |
5 | Output 2 | 13 | Output 3 | |
6 | Remote switch | 14* | Remote switch (Digital Ground) | |
7* | V- (Ground) | 15* | V- (Ground) | |
8* | V- (Ground) | Shell | Drain |
* Do not connect pin 10, 11 or 14 to Frame Ground (V-) or pin 7, 8 or 15 when one of these pins is connected to Frame Ground (V-).
Vehicle electrical system or harness
An alternate method to the "Remote Switch" is just to remove V+ power directly by the ignition switch or by the use of an in-line power-passing relay to the V+ of the EXRCPU or EXRLCPU. When using V+ to turn on the EXRCPU or EXRLCPU, the state of the CPU will be the last state when V+ was disconnected. For example, if the CPU was powered on when V+ was disconnected, then the CPU will power up when V+ is reconnected.