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Outputs Interface, PSM, Function - GF54.21-D-3002P

MODEL 906 with CODE ED5 (Parameterizable special module (PSM)) with CODE XM0 (Facelift) 

MODEL 906 with CODE ED8 (Preinstallation for parameterizable special module (PSM)) with CODE XM0 (Facelift) 

Discrete outputs 

The discrete outputs include high-side outputs, low-side outputs and outputs with extended functions. Each internal input on the "Outputs" module must be linked to a signal ID. Simplified illustration: Each output must be assigned to a signal. Unused outputs must be deactivated using the "Permanent LOW" signal. The permanently assigned properties must be defined during parameterization. Various properties must be changed in the case of outputs with extended functions. All outputs have short circuit detection and overload detection. The respective outputs are switched off if a short circuit or overload is detected. Up to 5 attempts are made to switch on the output again at an interval of 1 s. A fault entry is made if these attempts to switch the output back on fail.

The output remains deactivated. A further 5 attempts to switch on the output again are made after a change in status from "Circuit 15R OFF" to "Circuit 15R ON" and when overvoltage or undervoltage returns to normal voltage.

IMPORTANT Before a new request from the output can be made, the request must be canceled for at least 10 s.

Additional technical information on the outputs such as, e.g. the undervoltage and overvoltage protection limits or the internal wiring, is available in the "Technical data" documents.

The load capacity of the outputs is configured for ohmic loads. For loads with increased switch-on current (e.g. bulbs, capacitive loads) the nominal loads are reduced or shutdown can occur because of a detected short circuit or overload.

In order to protect the vehicle wiring in the event of the current at Circuit 30.1 or Circuit 30.2 exceeding 25 A, the outputs concerned are deactivated in the following sequence:

High-side outputs 

The high-side outputs enable almost all the signals in the signal pool to be assigned. The status is output in the case of bit signals. The output is switched on using byte, internal and pulse width modulated signals when the signal value is Not Equal 0.

Low-side outputs 

The low-side outputs enable almost all the signals in the signal pool to be assigned. The status is output in the case of bit signals. The output is switched on using byte, internal and pulse width modulated signals when the signal value is Not Equal 0.

Outputs with extended functions 

With output 01 and 02, the switching direction can be set to high-active or low-active. If these two outputs are used as a full bridge, it is important to observe the notes given in the description of this parameterization option. Outputs 09 and 10 can optionally issue a pulse width modulated signal or a digital signal (discrete output).

Function example 

External socket with activation by additional input 

A 12-V power outlet should be realized using a parameterizable special module, which provides a voltage of 12 V as soon as a load is connected. In addition to this, it is also possible to specifically activate or deactivate the 12 V socket through a signal from the PSM control unit (e.g. emergency off or "External socket active" control in the vehicle).

Parameterization of output 04 

The "Input 01 (high-active)" signal is used (signal ID 1013).

Properties of output:

Parameterization of current threshold for deactivation of output 04 = 0.5 A 

This parameterization provides the following function.

When the PSM control unit is in rest mode, then the PSM control unit can be woken by applying a load. After waking up, the PSM control unit immediately switches the output 04 active when the input 01 is active. The current is measured one second after the output is switched on. If the current is below the parameterized value threshold of 0.5 A, the output is deactivated again.

If a current higher than the parameterized threshold is permanently applied, the output remains active and can be deactivated again by reducing the operating current to match the vehicle status (not used in the example) or through deactivation of input 01. Following removal of the load and the resulting drop in current, the output is deactivated and detection of load connection is reactivated after 1 s. The output can then be activated again by reconnecting a load.

If no load is applied, then the PSM control unit can go into rest mode again, provided that no other conditions for keeping awake are active.

Input or output 

With this option, all outputs can also be used as discrete inputs. All high-side outputs give high-active inputs and all low-side outputs give low-active inputs. The half-bridge outputs 01 and 02 are always high-active inputs, irrespective of their polarity. The states of the inputs are made available in the signal pool.

If an output is to be used as an input, then the output must be assigned to the "Permanently LOW" signal, signal-ID 1000.

The input states in the signal pool are updated regardless of this parameterization, and can also be used as feedback for logic operations. Parameterization as an input therefore only prevents activation of the output.

External pull-up resistors or pull-down resistors must be used if the outputs (with the exception of outputs 03, 04, 05, 06 and 09) are used as inputs. With the outputs 03, 04, 05 and 06, the internal pull-up resistors must be deactivated if these outputs are used as inputs. In the case of output 09 the pull-down resistor must be connected for use as an input.

IMPORTANT The pull-up resistor (at low-active) or the pull-down resistor (at high-active) should have a value of approx. 1 kΩ.

The outputs 17 to 20 can also be used as high-active inputs. The pull-up resistors or pull-down resistors can be switched on or off through a parameterization option on each internal input on the "Outputs" module. The previously mentioned external pull-up resistor, for detection of a low level, should not be connected in this case. The signal detected at the output is inverted relative to the externally pending signal. This means that if the output is open, a logical "1" is detected. If 12 V are applied at the output, a logical "0" is detected.

Pull-up resistors 

Pull-up resistors can be switched on in outputs 03, 04, 05 and 06. At output 09 a pull-down resistor can be switched on (to generate a low-active pulse width modulated signal).

The values of the pull-up resistors or pull-down resistor are arranged in the following table:

Output resistance value 

Designation Signal identification(1) Logic Switching threshold (typical) at 25 °C Switching threshold, minimum and maximum values ON Switching threshold, minimum and maximum values OFF
Output 01 Actual value of output 01 High-active 5.6 V > 6.7 V < 3.4 V
Output 02 Actual value of output 02 High-active 5.6 V > 6.7 V < 3.4 V
Output 03 Actual value of output 03 High-active 5.6 V > 6.7 V < 3.4 V
Output 04 Actual value of output 04 High-active 5.6 V > 6.7 V < 3.4 V
Output 05 Actual value of output 05 High-active 5.6 V > 6.7 V < 3.4 V
Output 06 Actual value of output 06 High-active 5.6 V > 6.7 V < 3.4 V
Output 07 Actual value of output 07 High-active 5.6 V > 6.7 V < 3.4 V
Output 08 Actual value of output 08 High-active 5.6 V > 6.7 V < 3.4 V
Output 09 Actual value of output 09 High-active 5.6 V > 6.7 V < 3.4 V
Output 10 Actual value of output 10 High-active 5.6 V > 6.7 V < 3.4 V
Output 11 Actual value of output 11 Low-active 5.6 V < 3.4 V > 6.7 V
Output 12 Actual value of output 12 Low-active 5.6 V < 3.4 V > 6.7 V
Output 13 Actual value of output 13 High-active 5.6 V > 6.7 V < 3.4 V
Output 14 Actual value of output 14 High-active 5.6 V > 6.7 V < 3.4 V
Output 15 Actual value of output 15 High-active 5.6 V > 6.7 V < 3.4 V
Output 16 Actual value of output 16 High-active 5.6 V > 6.7 V < 3.4 V
Output 17 Actual value of output 17 Low-active 5.6 V < 3.4 V > 6.7 V
Output 18 Actual value of output 18 Low-active 5.6 V < 3.4 V > 6.7 V
Output 19 Actual value of output 19 Low-active 5.6 V < 3.4 V > 6.7 V
Output 20 Actual value of output 20 Low-active 5.6 V < 3.4 V > 6.7 V
IMPORTANT
(1) The respective signal number can be found in the "Signal lists" documents.

PWM output (with output 09 and 10) 

This setting enables the outputs 09 and 10 to be used as discrete outputs or as PWM outputs. If a pulse width modulated signal is issued, a signal is output as a pulse-width modulated signal (e.g. travel distance or circuit 58d). It must be remembered that here the load should be restricted due to the electromagnetic compatibility (EMC).

When using a PWM signal, it is strongly recommended to supply ground for the load through the pulse width modulated control unit (preferably through a low-active output). Operating currents up to approx. 100 mA can also be issued in an emergency without feeding back the ground line. Feedback of the ground supply for the load via the PSM control unit is an essential requirement for loads up to approx. 750 mA. A pulse width modulated signal should not be used in combination with higher operating currents.

IMPORTANT In the case of parameterization as a PWM output, it is not possible to use the output as an input. The PWM output option has higher priority.

Parameterization options 

The options which can be set for every output are listed in the overview "Parameterization options for outputs" in the document "Parameterization, PSM, function".

Open circuit recognition 

With this option, an output can be configured in such a way that an open circuit fault is stored when a load current threshold of approx. 5 % of the nominal current is underranged. This function is only supported by outputs 01 to 12.

Short circuit recognition 

This function is supported by all outputs and cannot be deactivated.

wake capability and load detection 

The outputs 03, 04, 05 and 06 can be parameterized capable of waking. In the case of a parameterized wake-up capability the output affected is activated by a 1 → 0 signal edge and a PSM control unit in rest mode is awoken.

Following activation of the output, it can then be deactivated through a parameterized signal or if it drops below the parameterized current threshold. To enable the operating current to enter a transient state, this is measured for the first time 1 s after output activation. For reliable detection of the 1 → 0 signal edge, each pull-up resistor on the output must also be parameterized to be active.

High-side or low-side 

This setting is preset for outputs 03 to 20 and cannot be changed. It must be assigned the settings given in the overview table. In the case of the half-bridge outputs 01 and 02 their switching direction can be selected via the parameterizing options.

Pulse width modulation soft start 

If a PWM output is used as a switch (not a pulse width modulated signal, but rather a normal discrete output), a soft start can then be activated. In the process when switching on first for 100 to 200 ms (typical 150 ms) an 80 percent PWM is output, before the output is fully controlled. This allows, for example, bulbs to be switched on safely and more smoothly.

Parameterizable dependence of outputs on vehicle status 

The adjustable dependencies for each output are described below. If more than one dependence is selected, an AND operation is applied between the individual dependencies. The output is then only active if all dependencies are fulfilled. The output becomes inactive as soon as a dependence is no longer fulfilled.

Deactivation for faulty interior CAN 

The output is then only active if the network management does not signal any CAN-B fault.

If this configuration bit is set, limp-home operation of the CAN-B (e.g. with cable break) also results in deactivation of the output.

Deactivation in case of parameterized undervoltage 

The output is only active if the parameterizable undervoltage detection of the PSM control unit is in the "Normal" or "Undervoltage detected" state. If it changes to the "Undervoltage aborted" state, the output is inactive.

Circuit 61 

Only ACTIVE for circuit 61 ON.

Circuit 15 

Only ACTIVE for circuit 15 ON.

Circuit 15R 

Only ACTIVE with circuit 15R ON

Circuit 15C 

Only ACTIVE with circuit 15C ON

Only ACTIVE with unlocked vehicle 

The "Vehicle locked" signal is set when the vehicle is unlocked using the transmitter key or when "Circuit 15C ON" is active. "Vehicle unlocked" is reset with "Circuit 15C OFF" when the vehicle is locked using the transmitter key. The output is only active if the "Vehicle unlocked" signal is set.

ACTIVE during control unit power-down 

The output is only active for as long as the run-on time for the PSM control unit has not yet expired. For more detailed information, see the chapter "Global functions" in the document "Functional scope of global functions, PSM, function".

Full-bridge mode (with output 01 and 02) 

If the signal parameter "Full-bridge mode" is set for each of the two half-bridge outputs 01 and 02, the two asymmetric half-bridges are connected together to form a full-bridge. If this is only done for one of the outputs, the full-bridge mode is not activated.

In addition, you must assign signals to the outputs to allow the full-bridge to be controlled. The signals of the two outputs then assume the following function:

Signal value for output 1 State of output 1 (circuit) State of output 2 (circuit)
0 Low-side (ground connection) High-side (+12 V)
1 High-side (+12 V) Low-side (ground connection)

The following restrictions apply in this operating mode:

The full-bridge is switched over according to the following sequence:

Activation or deactivation of the full-bridge therefore requires approx. 20 ms, and switchover of the full-bridge requires approx. 220 ms. The full-bridge is activated in stages. The respective low-side is activated first, followed by the respective high-side after 10 ms. The full-bridge is deactivated in the reverse order.

IMPORTANT The output 01 (pin 13) specifies the direction of rotation or polarity of the electric motor. Output 02 (pin 16) is used to activate the electric motor.

Example: Actuation of an electric motor on PSM control unit 

G10887849Courtesy of MERCEDES-BENZ USA

Parameterization options of outputs 

The parameterization options for discrete outputs are shown in the following.

Output Pulse width modulation soft start Wake capability Open circuit recognition Pull-up resistor PWM output Full-bridge mode
Output 01...02 No No Yes No No Yes
Output 03...06 No Yes Yes Yes No No
Output 07...08 No No Yes No No No
Output 09 Yes No Yes Yes Yes No
Output 10 Yes No Yes No Yes No
Output 11...12 No No Yes No No No
Output 13...20 No No No No No No
Parameterizable special module (PSM) control unit component description GF54.21-D-5005P