End Panel Description:
The following are in order from left to right as you look at the end of the SSS2:
- Vehicle Interface Cable with a Male/Female 9-pin connector. This connector enables you to compose multiple SSS2 units to create a system of interconnected ECUs.
- USB interface cable to communicate with a computer over a USB/Serial connection. The drivers for this connection are included in the Smart Sensor Simulator Interface Software.
- Power input from a +12VDC source. The SSS2 uses a Kycon KPJX-4S-S jack and the power supply uses a Kycon KPPx-4P plug.
- The Red LED indicator shows solid red when the unit is powered up. If J1939 network traffic is present, this LED will flicker at a rate reflecting the J1939 busload.
- The Green LED indicator shows when the key switch is on. If there is network traffic on the J1708 network or the second CAN channel, this LED will flicker.
- User input knob. Pressing this knob for more than 2 seconds can cycle the key switch relay. The key switch relay is also controlled from the SSS Interface software.
Definitions and Capabilities:
CAN – Controller Area Network up to 1M bits/sec
LIN – Local Interconnect Network. This is programmed to simulate the shifter lever on Freightliners with an automated transmission.
PWM – Pulse Width Modulated with adjustable frequency and duty cycle. These are 0 to 5V square wave signals.
The digital potentiometers are 12V tolerant devices with independent terminal connection control. A potentiometer has three terminals: Terminal A, the Wiper, and Terminal B connected to ground. The potentiometer is rated to have a resistance from Terminal A to Terminal B. The wiper picks off from along the resistor string. The terminals can be configured to open and close independently. This gives you the ability to connect the potentiometer as a voltage divider, resistance to ground, or resistance to a high source. The terminals are connected by selecting the checkboxes on the SSS Interface under the Digital Potentiometers tab.
Digital potentiometers can simulate signals that are used for
- Temperature Sensors
- Pressure Sensors
- Analog Accelerator Pedals
- Actuator Presence (i.e. the presence of an actuator)
The digital potentiometers used in the SSS2 are the MCP41HV51 and MCP45HV51. The digital potentiometers have a limit such that the wiper plus the terminal is between 250 to 300 ohms.
Analog outputs generate signals from 0 to 5 V. The signal is generated by a Digital to Analog Converter (TI DAC7678) and buffered with an op-amp. Each signal is capable of sourcing 25 mA.
Analog Outputs can simulate signals for:
- Pressure Sensors
- Switches to ground (by setting the output voltage to 0)
Analog outputs are similar to a voltage divider when examining the signal with a meter. However, voltage dividers based on a potentiometer sink current and Analog outputs can both sink and source current.