Version 2.0.3 Preliminary Documentation – May be Subject to Change 5-36
1.2.
Description of ECU
The 16 Analog I/O electronic control unit (ECU) is a device intended to provide control of up to
eight analog signal level outputs over a J1939 network. Each output channel could be
independently configured to be either a –5V to 5V, 0 to 5V, -10V to 10V, 0 to 10V, 0 to 20mA or 4
to 20mA output. Each output has associated with it an AGND reference pin.
The ECU also has eight analog inputs which can be independently configured to accept a 0 to 5V,
0 to10V, 0(4)-20mA, PWM, Frequency/RPM, 16-bit Counter, or an active high digital input. Each
input has associated with it an Analog Ground (AGND) reference pin, and a +5V or 20mA
reference pin. Inputs can be configured to periodically send the measured input data to a J1939
CAN network.
As an alternative to being controlled by a message received from the CAN bus, an output could be
configured to use any of the on board inputs as either a control signal or an enable signal.
For more information about the I/O specifications, refer to Technical Datasheet TDAX030200.
1.3.
Description of Analog Inputs
Each analog input can be configured for any one of the following options, and the properties and
behavior of the input in each mode is described below. Unless noted otherwise, the reference pin
associated with each input channel is set to +5V. See section
4.1
for more information.
Input Disabled:
The input is not used, and no CAN messages associated with this channel will
be sent to the network.
0 to 5 Volt:
The input is configured to accept a voltage input in the range of 0 to 5V.
Signals above 5V will be rectified to 5V. The ECU will interpret the offset in
volts and the resolution setpoint as V/bit, when sending the message. Error
detection setpoints will be interpreted in volts.
0 to 10 Volt:
The input is configured to accept a voltage input in the range of 0 to 10V.
Signals above 10V will be rectified to 10V.The ECU will interpret the offset in
volts and the resolution setpoint as V/bit, when sending the message. Error
detection setpoints will be interpreted in volts.
0(4) to 20 Milliamp: The input is configured to accept a current input in the range of 0 to 20 mA.
Signals above 20mA will be rectified to 20mA.The ECU will interpret the offset
in milliamps and the resolution setpoint as mA/bit, when sending the message.
Error detection setpoints will be interpreted in milliamps. In this mode, the
reference pin associate with the input channel will source a constant 20mA.
PWM Duty Cycle: The input is configured to measure the duty cycle of a pulse width modulated
(PWM) signal in the range of 0 to 100%dc. The ECU will interpret the offset in
percent duty cycle (%dc) and the resolution setpoint as %dc/bit, when sending
the message. Error detection setpoints will be interpreted in %dc.
