Saia-Burgess Controls AG
Manual
Manual PCD 1 / PCD 2 Series
│ Document 26
/
737 E
N22 │ 2013-11-26
4
Communication interfaces
4-46
MP-Bus PCD2.T500
4.11.6 Communications times for MP-Bus
For each instruction transmitted via the bus, an average communications time of ap-
prox. 150 milliseconds is required (a command always consists of an instruction and
an answer). The following values are identical for both damper and valve actuators.
1. Example with one MFT(2) actuator
The master sends a setpoint to the MFT(2) actuator (1st command).
The master reads the actual value from the MFT(2) actuator (2nd command).
The entire communications process therefore comprises 2 commands of 150 ms =
approx. 300 ms.
2. Example with two MFT(2) actuators
The master sends one setpoint each to MFT(2) actuators
1…8 (total commands: 8).
The master reads actual values from the MFT(2) actuators
(total commands: 8).
The entire communications process therefore comprises 16
commands of 150 ms = approx. 2.4 s
4.11.7 Calculation of line length
Connection of MP-Bus
The network consists of a 3 - wire connection (MP
communication and 24 V
supply).
Special cable or line termination resistors are not
required.
Line lengths are limited
by the total power rating for all connected
MFT / MFT2 actuators,
by the type of supply (24 V
AC
or 24 V
DC
via the bus)
and by the conductor cross-section.
Distance table for the MP-Bus
Supply
maximum line lengths with 1.5 mm
2
cable
Total power consumption [Watt]
5
10
15
20
25
30
35
40
max. line length*
24 V
DC
300
150
100
85
60
50
42
38
24 V
AC
200
120
80
55
45
38
32
28
* all distance data are approximately and can deviate from the local condition
By bigger cross sections of the cable, the
distances can be increased.
The maximum length of 800
meters can be
reached, when the drives are supplied locally via
a separate transformer with 24 V
AC
Further data concerning distances
and connection types are offered by
BELIMO
Automation AG
Master
MP-Bus
1
2
3
4
5
6
7
8
Master
MP-Bus
