Basic Documentation

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Aggregates 03.10.2011
10.6.4 Cascade step switches
To increase the number of steps, two or three linear/binary step switches can be
interconnected (cascaded).
Main menu > Commissioning > Extra configuration> Aggregates > Step switch > Step
switch 1…2 >
Operating line Range Factory setting
Connect 1+2 No, Yes No
Connect 2+3 No, Yes No
 If two linear/binary step switches are interconnected (cascaded), the outputs of
the sequence controller must be connected only to the first step switch
 The modulating output of the 2nd (with 2) or 3rd (with 3) step switches must be
configured as modulating load signal
 The type of both step switches should be equal: binary or linear
 Cascading is without effect, if the 2nd step switch is inactive
 There may not be gaps in configuration; thus, steps 1, 2 and 3 rather than steps
1, 3 and 4
 If two or three step switches are cascaded, the settings for locking time, overrun
time, startup delay (linear only) as well as external release must be set for all
step switches; the settings are not passed on
 Startup delay (linear only) and run priority changeover act only within the
respective step switch
Binary step switch cascaded at 256 load increments:
N.X1
Y
SIGNAL Y
x
A7.Q1
Q
A7.Q2
Q
Q
N.Q2
Q
N.Y1
Y
N.Q3
Q
N.Q1
N.Q6 N.Q7
QQ
Q
N.Q4
123
4
y1 y2
x
QQ Q
QY
y3
123
4
y1 y2
x
QQ Q
QY
y3
730
720
730
730
730
S1 S2 S3 S4S5 S6 S7 S8 Y
S3 S2 S1 S4 S5
yp yp yp yp yp
a
d



Step
switch 1
Linear
Binary
Release
Connect 1+2
Step
switch 2
Linear
Binary
Release
Connect 2+3
SAT
Controller 1
(Ventilation)
With supply air limitation
Cascade
Constant (supply air)
Cascade/const (alternating)
Seq. limit. Casc/Const
3150s50en
The greater load increments (S5 to S8) of the first step switch are subdivided by
the smaller increments (S1 to S4) of the second step switch.
Step switch 1: Greater load increments.
4 Q S5 = 16/256 S6= 32/256 S7 = 64/256 S8 = 128/256
Step switch 2: Smaller load increments.
1Y+4 Q Y = 0.. 1/256 S1 = 1/256 S2 = 2/256 S3 = 4/256 S4 = 8/256
Configuration
Notes on configuration
Example 1
Load connection