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Input Interface, PSM, Function - GF54.21-D-3001P

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 inputs 

Positive active inputs 

The states of the outputs are collected in the signal pool.

Ground-active inputs 

The states of the outputs are collected in the signal pool.

If the pull-up resistors at the low-active inputs are deactivated, these inputs can be used as high-active inputs. The detected signal is then inverted relative to the externally pending signal. This means that if the input is open, a logical "1" is detected. If 12 V are applied at the input, a logical "0" is detected.

Analog inputs 

The analog input values are normalized with the supply voltage of the PSM control unit via an algorithm, then a threshold value evaluation takes place. The threshold value is underranged in the case of an active switch (low-active). The signal receives the logical status "active".

If no potential is applied at the input (i.e. open line), certain analog levels are present as a result of the internal wiring. In order to use the input as a high-active input, a pull-down resistor (at least approx. 1 kΩ) must be connected to the relevant input. This reduces the level for "no potential applied/open line", thereby making detection more reliable.

When a voltage is applied to the input, a corresponding current flows via the pull-up resistor.

In order to use the analog inputs as a digital ground-active input, the signals in the signal pool which are intended for this purpose are used.

The analog values and normalized analog values of the inputs are available as signals in the signal pool.

IMPORTANT Further information can be found in the "Technical data" documents.

Parameterization options for inputs 

The properties of the discrete inputs regarding wake capability and activation of pull-up or pull-down resistors and type of input (switch or push button switch) can be changed using XENTRY Diagnostics. The various setting options are listed in the table below.

Input Wake capability Pull-up resistor Switch/push button switch Evaluation type
Inputs 01...03 Yes - Yes -
Inputs 04...06 Yes Yes Yes -
Inputs 07...08 Yes - Yes 2-stage threshold switch
4-stage threshold switch
8-stage threshold switch
Taxi alarm button
Taxi alarm reset button
Freely parameterizable thresholds
Inputs 09...10 - - Yes 2-stage threshold switch
4-stage threshold switch
8-stage threshold switch
560 Ω shift paddle
Freely parameterizable thresholds

Input type, status-controlled or edge-controlled, switch or push button switch 

G10887847Courtesy of MERCEDES-BENZ USA

IMPORTANT When using a discrete input, it is important to note that the discrete input must be parameterized to "Switch" or "Status-controlled" if a function where it is also possible to parameterize the "Switch/Push-button switch" or "Status-controlled/edge-controlled" option (e.g. alarm functions or light functions) is triggered.

wake capability or activating pull-up or pull-down resistors 

All inputs can wake the PSM control unit both with the positive edge and with the negative edge. Only the two analog inputs 07 and 08 can wake the PSM control unit with just a negative edge (high-low change at the respective connector pin).

The PSM control unit can thus also go into idle mode with switched-on inputs and nevertheless still register each change in the inputs.

IMPORTANT The low-active inputs 04, 05 and 06 can then only be capable of waking, when the associated pull-up resistors are activated.

With deactivated pull-up resistors and activated wake capability the undefined level of an open or unassigned can wake the PSM control unit when it is not desired.

If therefore one of these inputs is parameterized as capable of waking, the wake capability is only enabled by the activation of the associated pull-up resistor. If the pull-up resistor is not activated, the PSM control unit cannot be woken up using this input. Your external wiring configuration may make it necessary to deactivate the pull-up resistors.

If one of the inputs 04, 05 and 06 is parameterized as not capable of waking, then its associated pull-up resistor is switched off in each case when entering rest mode, in order to spare quiescent current.

Types of evaluation of 4 analog inputs 07, 08, 09 and 10 

Along with its evaluation as a digital input and the alternate usage of the measured voltage value at the input, the analog inputs 07, 08, 09 and 10 can also be evaluated in a 3rd way as a multistage threshold switch. For this purpose, the measured input voltage is set in proportion to the current supply voltage of the PSM control unit. The thresholds of the threshold switch can then be specified as a percentage of the supply voltage. This enables evaluation independent of the supply voltage.

IMPORTANT If no potential is applied at the input (i.e. open line), certain analog levels are present as a result of the internal wiring. If you want to use the input as a high-active input, you should connect a pull-down resistor (at least approx. 1 kΩ) to the input. This reduces the level for "no potential applied/open line", thereby making detection more reliable. If you apply a voltage to the input, a corresponding current flows via the pull-up resistor.

To simplify matters, a number of thresholds have been predefined for certain application types and can be assigned separately for each of the 4 inputs in the properties of the discrete inputs.

To remain flexible, however, it is possible to parameterize thresholds manually for each input. These thresholds can be set in a separate submenu for the switching thresholds under the evaluation type "Parameterizable thresholds" in the properties. The results of the evaluations are made available in the signal pool for further use.

With input 07, it is the following 8 bit signals:

The voltage value at the analog input is in the signal pool (e.g. input 07: "Input voltage", signal ID 3033). In the case of a configuration with e.g. one potentiometer, however, this value would depend on the supply voltage. The voltage ratio normalized to the supply voltage of the PSM control unit is also in the signal pool (e.g. input 07: "A/D value of input 07", signal ID 2022).

This value can be converted using the following formula so that it corresponds to the percentage value of the current input voltage relative to the supply voltage:

The following reference values exist:

IMPORTANT In the case of the menu item "Display signal values", the values read out from the control unit are shown in hexadecimal notation. To be able to determine the percentage, the displayed hexadecimal A/D values must be manually converted into decimal values.

Example 

The value of the signal "A/D value of input 07" (signal ID 2022) is output with "002C" via XENTRY Diagnostics in the "Actual values" tab, menu item "Display signal values". Since the high byte is at the first position and the low byte at the second position, this results in a numerical value of 0x002C (hex). When converted, this gives a numerical value of 44 (dec).

Applying the formula results in a percentage of 46 %. This means that, with a supply voltage of 12 V, a voltage of 0.46 x 12 V = 5.5 V is applied at input 07. In the following the preassignments are explained first and then the calculation of the freely adjustable thresholds.

Evaluation types - Stage threshold switches 

For all stage threshold switches, the stages are assigned relative to the supply voltage at the PSM control unit.

Evaluation type 2-stage threshold switch 

Evaluation type 4-stage threshold switch 

Evaluation type - 8-stage threshold switch 

Evaluation type - 'Activate emergency alarm' button (only with input 07 and 08) 

Evaluation type - 'Deactivate emergency alarm' button (only with input 07 and 08) 

For all stage threshold switches, the stages are assigned relative to the supply voltage at the PSM control unit:

Type of evaluation 560-Ω gearshift paddle (only for input 09 and 10) 

Evaluation type - Free parameterization of thresholds 

Parameterization of inputs 07 to 10 

In the menu item "Properties - Switching thresholds for analog inputs 07 to 10", the threshold values can be set for each of the 4 analog inputs. This allows the thresholds to be adapted to individual requirements. The thresholds are entered in percent (see calculation of percentage above).

Values above 100 % are also possible, although there is a slight drop in accuracy with values above 150 %. Threshold switches with various thresholds, the analysis of which is dependent on the supply voltage, can thus be implemented quickly and simply. Unused thresholds must be assigned 255 %. The thresholds must be entered in ascending order to ensure that they function correctly. The gap between 2 thresholds should be at least 2 %.

Example 1: 3-stage evaluation 

The assignment of 2 thresholds is necessary for preparing a 3-stage threshold switch.

In the example given, the 1st threshold lies at 50 % of the supply voltage and the 2nd threshold at 80 % of the supply voltage. The parameterization is then as follows:

IMPORTANT Thresholds 3 to 7 are not used and must therefore be set to 255 %.

With this threshold assignment, it is for example possible to monitor a voltage range and to receive signals for underranging (stage 0), overranging (stage 2) and for correct position (stage 1).

Example 2: 8-stage evaluation 

To create an 8-stage threshold switch, it is necessary to assign all 7 thresholds. In the example, a voltage divider which can move between 30 and 70 % of the supply voltage is to be monitored.

The parameterization is then as follows:

Thus in the area between 30 and 70 % 8 stages are produced, with which in a further processing (e.g. programmable logic controller (PLC)) arbitrary control functions can be realized.

Parameterizable special module (PSM) control unit component description GF54.21-D-5005P
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