PSM Arithmetic, Example Of PSM Function - GF54.21-S-3055-01TRC

Model 447

With Code ED5 (Parameterisable special module)

Except Code XM7 (MOPF II)

Speed signal, differentiator/integrator

Model 448

With Code ED5 (Parameterisable special module)

Except Code XM7 (MOPF II)

Speed signal, differentiator/integrator

Courtesy of MERCEDES-BENZ USA

Speed signal function blocks

The speed signal (interior CAN (CAN B): "VehSpd_Disp") can be output at one of the pulse-width-modulation-compatible outputs.

Formula: Pulse [1/s] = (Speed [km/h] * 4 [pulse/m])/3.6

Value range for speed	4...409.4 km/h
Value range of pulse width modulated signal	0...100 %
Pulse length	200 Hz

4 pulses/m are output. The pulse width is 4 ms.

At 112.5 km/h, the pulse duration is the same as the pulse pause. This 1:1 ratio is maintained up to higher speeds.

In other words, at higher speeds the pulse length and pause length shorten at the same time.

The speed signal is implemented via the blocks of the programmable logic controller (PLC), arithmetic unit and multifunction output blocks. The picture shows the simplified function block operation.

The configuration is available in the tables.

Function description of implementation

Comparator 2, calculation step 1 (Comp 2):

Limit valid value range of input signal from 0 to 4094 (0 to 409.4 km/h). Values above 4094 are set to 0

Arithmetic block 3, calculation step 2 (Calc 3):

Multiply input signal by number of pulses/m

Arithmetic block 4, calculation step 3 (Calc 4):

Conversion of number of pulses to cycle duration

Arithmetic block 5, calculation step 4 (Calc 5):

Calculate pulse duration from cycle duration

PLC G11 threshold switch(S):

Define ranges of cycle duration
0 to 800: A = 1
801 to 22 727: B = 1
> 22 727: C = 1

PLC G12 value table 1 (WT1):

Depending on result of threshold switch
A = 1 → Duty cycle = 50 % of cycle duration (result of arithmetic block 5, calculation step 4)
B = 1 → Duty cycle = Constants (4 ms)
C = 1 → Duty cycle = 0; pulse width modulation (PWM) is switched off

Multifunction output block (MFA 6):

The cycle duration and pulse duration are output depending on the input signal.

Signal identification number = Signal ID. The signal IDs are notated in hexadecimal form.

ARITHMETIC UNIT - COMPARATOR 2, CALCULATION STEP 1 (COMP 2), CONFIGURATION

Input	Signal name	Signal ID	Comparison assignment
Compare_2_a	Out_AU_Const_3	0x8042	Input a (a) > Input b (b)
Compare_2_b	VehSpd_Disp	0x3023
Compare_2_c	VehSpd_Disp	0x3023
Compare_2_d	Const_Bit_0	0x1000

ARITHMETIC UNIT - ARITHMETIC BLOCK 3, CALCULATION STEP 2 (CALC 3), CONFIGURATION

Input	Signal name	Signal ID	Upper limit value	Lower limit value
Calc_3_a	Out_AU_Compare_2	0x8025	16 376	0
Calc_3_m1	Out_AU_Const_4	0x8043
Calc_3_m2	Const_Bit_1	0x1001
Calc_3_b	Const_Bit_0	0x1000

ARITHMETIC UNIT - ARITHMETIC BLOCK 4, CALCULATION STEP 3 (CALC 4), CONFIGURATION

Input	Signal name	Signal ID	Upper limit value	Lower limit value
Calc_4_a	Out_AU_Const_5	0x8044	3 600 000	0
Calc_4_m1	Const_Bit_1	0x1001
Calc_4_m2	Out_AU_Calc_3	0x8002
Calc_4_b	Const_Bit_0	0x1000

PLC G11 THRESHOLD SWITCH (S), CONFIGURATION

Input	F1	F2	F3	F4	F5	F6	F7	F8	F9	F10	F11	F12	F13	F14	F15	F16	Signal name	Signal ID	Mode	Sequential point (1)
SS1_1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	Out_AU_Calc_4	0x8003	Threshold A	0
																			Threshold B	800
																			Threshold C	22 727
																			Threshold D	65 535

ARITHMETIC UNIT - ARITHMETIC BLOCK 5, CALCULATION STEP 4 (CALC 5), CONFIGURATION

Input	Signal name	Signal ID	Upper limit value	Lower limit value
Calc_5_a	Out_AU_Calc_4	0x8003	400	0
Calc_5_m1	Const_Bit_1	0x1001
Calc_5_m2	Out_AU_Const_6	0x8045
Calc_5_b	Const_Bit_0	0x1000

PLC G12 VALUE TABLE 1 (WT1), CONFIGURATION

Input	Signal name	Signal ID	Value table 1	Default value (signal name)	Const_Bit_0	0x1000
WT1_1 (Value 1)	Out_G11_SS1_A	0x11D3	-	Value 1 (Signal name)	Out_AU_Calc_5	0x8004
WT1_2 (Value 2)	Out_G11_SS1_B	0x11D4	-	Value 2 (Signal name)	Out_G12_K1_Value	0x308C
WT1_3 (Value 3)	Out_G11_SS1_C	0x11D5	-	Value 3 (Signal name)	Const_Bit_0	0x1000
WT1_4 (Value 4)	Const_Bit_0	0x1000	-	Value 4 (signal name)	Const_Bit_0	0x1000

ARITHMETIC UNIT - CONSTANTS BLOCKS, CONFIGURATION

Constants block (KB_1)	Arithmetic unit	Meaning
Konstante 3	4094	Maximum reception value
Konstante 4	4	Number of pulses per meter
Konstante 5	3 600 000	Speed factor in cycle duration
Konstante 6	2	Pulse duration factor

PLC G12 VALUE TABLE 1 (WT1), CONFIGURATION

Konstantenblock 1 (KB1)	Group 12	Meaning
Konstante 1	400	Pulse duration

MULTIFUNCTION OUTPUT BLOCK (MFA6) CONFIGURATION

1 A High Side, PWM	F1	F2	F3	F4	F5	F6	F7	F8	F9	F10	F11	F12	F13	F14	F15	F16	Signal name	Signal ID	Multifunction output block	-
Eingang1 (Active)	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	Out_AU_Com-pare_2	0x8025	-	Model	Output (1)
Eingang2 (Const/puls)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Const_Bit_0	0x1000		Reactivation attempts	1
Eingang3 (Cutoff reset)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Term15_Actv	0x1219		PWM type	Time (1)
Eingang4 (Cycle time)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Const_Bit_0	0x1000	-
Eingang5 (Pulse time)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Const_Bit_1	0x1001
Eingang6 (PWM active)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Out_AU_Com-pare_2	0x8025
Eingang7 (PWM period)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Out_AU_Calc_4	0x8003
Eingang8 (PWM duty)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	Out_G12_WT1	0x308B