GV75 User Manual
TRACGV75UM00112
Table 7: Electrical Conditions of Digital Outputs
Note:
1. The relay output can be latched by the software, so even if the GV75 is restarted or powered
down in some cases, the relay output will not change. To use the latch function, the main power
and backup battery should be connected. Otherwise the relay will always be in normal close status.
Digital outputs are used for cutting/restoring GND. The examples of connections are:
Figure 2: The Example of Connection to Drive an LED
Figure 3: The Example of Connection to Drive a Relay
Note: All outputs are internally pulled up to PWR pin by a diode. So no external flyback diode is
needed when the output is connected to an inductive load.
3.7.
UART Interface
There is one UART interface on GV75. UART is used for configuration and firmware
downloading, and communicating with external devices like CAN Bus module and RFID reader.
Please note the UART interfaces are all RS232 level. For RS232 level, valid signals are 3V to 15V
and -3V to -15V and the -3V to +3V is not a valid level. 3V to 15V correspond with logic 0 of TTL
level, while -3V to -15V correspond with logic 1.
The examples of connections of UART with female DB-9 and with external devices are showed
as follows.
Figure 4: The Connection of UART with Female DB-9
Logical State
Electrical State
Enable
<1.5V, drive current is 0.15A
Disable
Open or the pull-up voltage (max 32V)
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