Yokogawa AXFA14G/C - Manual (Page 8)

IM 01E20F12-01E 3-1
3. GETTING STARTED
3. GETTING STARTED
Fieldbus is fully dependent upon digital communica-
tion protocol and differs in operation from conven-
tional 4 to 20 mA transmission and the BRAIN
communication protocol.
HMI
Class I Master
I/O CARD, PLC, etc.
PROFIBUS-DP
PROFIBUS-DP devices
PROFIBUS-PA devices (AXF)
PROFIBUS-PA (31.25 kbps)
Class 2 Master
FieldMate (FDT/DTM)
PDM (EDDL), etc.
DP/PA
Coupler
F0301.EPS
Figure 3.1 Profibus System Construction
3.1 Connection of Devices
The following are required for use with PROFIBUS
PA devices:
• Power supply:
PROFIBUS PA requires a dedicated power supply.
It is recommended that current capacity be well over
the total value of the maximum current consumed
by all devices. Power is supplied by a DP/PA
coupler.
• Terminators:
PROFIBUS PA requires two terminators. A termina-
tor shall be located at each end of the trunk cable.
• Field devices:
Connect PROFIBUS PA communication type AXF
(Refer to section 8.3 terminal connection). Two or
more AXF devices or other devices can be con-
nected.
• DP/PA Couplers:
PROFIBUS PA requires DP/PA couplers which
convert the RS-485 signals to the IEC 61158-2
signal level and power the field devices via the
PROFIBUS PA.
• Cable:
Refer to Figure 3.1.
Table 3.1 PROFIBUS PA Cables and Transmissible Length
Type A: Individually-shielded
twisted pair cable
Type of cable
#18AWG
(0.82 mm 2 )
Cable
specifications
1,900 m
Max. length of
cable
(reference value)
1,200 m
400 m
200 m
#22AWG
(0.32 mm 2 )
#26AWG
(0.13 mm 2 )
#16AWG
(1.25 mm 2 )
Type B: Overall-shielded
twisted pair cable
Type C: Unshielded twisted
pair cable
Type D: Overall-shielded
non-twisted cable
T0401.EPS
Note: Yokogawa recommends the use of Type A.
Usage of Type B and D is restricted.
Yokogawa does not recommend the use of
Type C.
Before using a PROFIBUS PA configuration tool other
than the existing class 1 and class 2 Masters, confirm it
does not affect the loop functionality in which all
devices are already installed in operation. Disconnect
the relevant control loop from the bus if necessary.
IMPORTANT
• It is mandatory to turn on the power supply of
the AXF before turning on the power supply for
the Profibus line.
• Connecting a PROFIBUS PA configuration tool
to a loop with its existing class 1 and class 2
Masters may cause communication data
scrambling resulting in a functional disorder or
a system failure.