3.5 Characteristics
Setpoint value signal
Fig. 9: Characteristic of the setpoint value signal
1
Characteristic for signal voltage range 0 – 10 V DC
2
Characteristic for signal voltage range 2 – 10 V DC
q
v
Volume flow rate
Y Setpoint value input
The volume flow rate setpoint value must be specified
as follows, depending on the operating mode:
In analogue operation:
At terminal Y, a voltage
signal 0 – 10 V DC or 2 – 10 V DC,
0(2) V = q
vmin
, 10 V = q
vmax
In digital operation:
The setpoint value is specified
in Modbus register 0 as a percentage value.
[0 – 100%],
0% = q
vmin
, 100% = q
vmax
The relationship between the volume flow rate set value
and the associated voltage signal can be calculated
from the formula below. The setting for q
vmin
and q
vmax
must be taken into account.
0 – 10 V DC
× (q
– q
) + q
q
Y
10 V
=
vmin
vsoll
vmin
vmax
2 – 10 V DC
q
×(q
– q
)+q
Y– 2
(10 V– 2 V)
vsoll
=
vmax
vmin
vmin
Sample calculations
9.3.2 ‘Sample calculations’ on page 35
Actual value signal
Fig. 10: Characteristic of the actual value signal
1
Characteristic for signal voltage range 0 – 10 V DC
2
Characteristic for signal voltage range 2 – 10 V DC
q
v
Volume flow rate
U Actual value signal
The volume flow rate actual value can be tapped as a
voltage signal at the terminal (U). The measuring range
is factory-adjusted to the size of the VAV terminal unit,
so that the respectively device nominal volume flow rate
(q
vnom
) always corresponds to an actual value signal of
10 V DC. In digital and hybrid operation, the actual
value in Modbus register 6 can be read out as a per-
centage value of q
vnom
.
The current volume flow rate actual value can be calcu-
lated from the measured voltage at the output (U) using
the formula below.
0 – 10 V DC
q
× q
U
10 V
vist
vnenn
=
2 – 10 V DC
q
× q
U – 2
(10 V – 2 V)
vist
vnenn
=
Structure and functional description
Characteristics
Control component Compact XM0 • XS0 for VAV terminal unit TVE
15
