Chapter 7: sDIO Module NOTE: The off-state current range exceeds the leakage current of sDIO outputs. This guarantees that the inputs will not be turned on by the leakage current from the out- puts. This is useful in situations where the outputs are looped-back to the inputs for monitoring purposes. sDIO Outputs The 32 output channels are arranged in four groups of eight. Each group is isolated from the other groups and is optically isolated from the sDIO circuitry. The eight outputs within each group share a common power supply and a common ground. The outputs are accessed through the two female 44-pin D-sub output connectors on the front of the sDIO module.
Each connector provides access to two output groups. Each group requires 19 pins: 8 output signals, 1 test signal, 9 power supply (all tied together), and 1 power supply ground reference. When an output is on, current will flow in through the power supply pins and out through the output pins. This type of output is considered sourcing, that is, in the ON condition, current flows out of the output pin. See the figure Typical sDIO Output Wiring on page 73 for details on typical digital output wiring. Testing sDIO Outputs Like many solid-state I/O systems, when an output is off, a small leakage current will flow out of the output.
This will raise the potential of the output to the power supply voltage level if there is no load. With a load connected, the output will function normally. However, if you need to test the output with a voltmeter with a load disconnected, you will get a false reading. The test signal provides a bias that can be used as a pull-down resistor for system-level troubleshooting. When this is connected to an output, the output will assume the ground poten- tial when it is off. sDIO LEDs A pair of two-color LEDs on the sDIO module indicate link status over the IEEE 1394 con- nection and system status. The upper LED lights green when an IEEE 1394 connection is estab- lished.
The lower LED blinks green when the software is active and switches to solid green after the controller software has found and configured the DIO block. The lower LED lights solid red whenever an output fault (excessive current or temperature) is detected on any of the 32 outputs. Refer to the following table for information about the LEDs and the figure sDIO Connectors and Indicators on page 61 for information on their location. NOTE: A fault indication is the result of an over-temperature or over-current con- dition on one or more of the outputs, usually due to a short-circuit. As a result, the output driver IC will oscillate on and off as the chip tries to drive the load.
Note that this red fault LED is active only when: l An extended output (for example, a SIGNAL in the range of 33 to 64) has been turned on by an eV+ command. l An activated output has a thermal-overload problem, usually due to a short in the user’s wiring from the output pin to the user’s ground. SmartController EX User’s Guide, 11069-000 Rev. F Page 70 of 92