Technical Tip: Overview of the Digital Input/Output (DIO) Module in FortiGate Rugged 70F Series

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Description	This article discusses the usage of the Digital Input/Output (DIO) module on the FortiGate Rugged 70F Series.
Scope	FortiGate Rugged 70F (FGR-70F) Series, see Hardware Guide for reference.
Solution	The DIO module has 2 digital input terminals and 1 return terminal: IN1+, IN2+, and REF respectively. These input terminals can detect open/closed circuits, or sense voltage ON/OFF. The DIO module has 3 digital output terminals: NO, NC, and COM. These terminals are dry output as it does not supply power. The output terminals are rated to switch up to 30W when connected to external power. Resistive: 30VDC@1A and 125VAC 0.3A. DIO Module Features The common features of DIO Modules are: Withstand voltage applied at the terminal up to 60V. Protection from accidental application of reverse voltage. An LED indicator for active (ON) and non-active (OFF) signal. ESD air discharge passed at +/- 15kV. Optically and galvanically Isolated. The DIO Module Connector The following figure shows the DIO module connector on the FortiGate Rugged-70F series.   DIO Module Specifications Digital Input (DI) recommended operating conditions are described in the following tables. The input terminals can be configured by software for open/short detection (e.g., sending out test current); or digital detection (voltage ON/OFF). FortiOS is required to set the operation mode. The open/short detection is implemented with a resistor current, a limited voltage source of 12V. External input/device needs to be connected to this terminal to have low enough resistance during this ‘short’ to pass at least 1mA. Specification Minimum Unit Input Current for Detection -1 mA Table 1. Digital Input Recommended Operating Condition (open/short detection or current sourcing logic) Note: The current flowing out of the input terminal is sourcing, negative. The current flowing into the input terminal is positive. Terminals have internal current limiting resistors. Specification Minimum Maximum Unit Input Voltage High 4.6 48 Volts Input Voltage Low 0 3 Volts Input Current 1 8.8 mA Table 2. Digital Input Recommended Operating Condition (voltage detection).  Fig 1. Digital Input: Short/Open Detection   Fig 2. Digital Input: Voltage Detection Digital Output (DO) recommended operating conditions are described below. The relay contact is rated for 100000 full resistive load actuation at 30W. Contacts rated at 100 mOhm before normal degradation from regular use. The Max switching contact current is 1A. Max pulse carrying current is 2A. Fig 3. Relay Output: Indicator lamp Hardware Diagnostics Self-diagnostics can be run using the following command: diagnose hardware test alarm main Test most critical components of the DIDO circuit Please connect JIGs: COM <--> REF NC <--> IN1 NO <--> IN2 Do you want to continue this test? (y/n) (default is n) … ===================Fortinet Hardware Test Report ====================== ALARM   Test most critical components of the DIDO circuit............. PASS =================== Fortinet Hardware Test PASSED ====================