●
Lay cables being susceptible to interference or sources of interference at the
highest possible distance from each other.
●
The interference immunity of signal and fieldbus cables increases if the cables
are laid close to the earth potential.
●
If possible, avoid laying long cables and make sure that they are installed in
areas being subject to low interference.
●
Avoid parallel paths with little cable distance of cables being either susceptible
to interference or interference sources.
Fieldbus cable
Table 12:
Cable recommendation
Only cables complying with the recommendations of EIA 485 specifications should be used for Modbus
wiring.
135 to 165 Ohm, at a measurement frequency between 3 and 20 MHz
Impedance
< 30 pF per metre
Cable capacity
> 0.64 mm
Wire diameter
> 0.34 mm², corresponds to AWG 22
Cross section
< 110 Ohm per km
Loop resistance
CU shielding braid or shielding braid and shielding foil
Screening
Prior to installation, please note:
●
Connect maximum 32 devices to one segment.
●
If more devices are to be connected:
-
Connect several segments using repeaters.
●
Install fieldbus cables at a distance of minimum 20 cm to other cables.
●
If possible, fieldbus cables should be laid in a separate, conductive, and earthed
cable tray.
●
Ensure absence of equipotential earth bonding differences between the indi-
vidual devices at fieldbus (perform an equipotential earth bonding).
Table 13: Transmission rate/cable length for line topology
Possible cable length with repeater
(total network cable length)
Max. cable length (segment length)
without repeater
Baud rate (kbit/s)
Approx. 10 km
1,200 m
9.6 – 115.2
Table 14: Transmission rate/cable length for loop topology
Max. possible cable length of redund-
ant loop
Max. cable length between actuators
(without repeater)
Baud rate (kbit/s)
Approx. 290 km
1,200 m
9.6 – 115.2
22
SQ 05.2 – SQ 14.2 / SQR 05.2 – SQR 14.2 Control unit - electromechanical
Electrical connection
AC 01.2 Intrusive Modbus RTU
