MOVITRAC
®
31.. PROFIBUS Fieldbus Interface
11
Assembly / Installation
Instructions
2
The MOVITRAC
®
31.. frequency inverter is connected to the PROFIBUS system via a twisted,
screened two-wire cable. The connection of the two-wire cable to the PROFIBUS connector is via
pin 8 (A/A) and pin 3 (B/B). These two contacts are used for communication. The RS-485 signals
A/A and B/B must be contacted the same on all PROFIBUS stations, as otherwise communication
via the bus will not be possible.
Via pin 4 (CNTR-P) the PROFIBUS option pcb supplies a TTL control signal for a repeater (refer-
ence = pin 9).
2.4
Screening and Laying of the Bus Cables
The FFP 31 option pcb supports the RS-485 transmission technology and requires as a physical
medium a screened, two-wire twisted-pair cable (cable type A) specified for PROFIBUS in accord-
ance with EN 50170 V2 / DIN E 19245 Part 3 (
→
Appendix).
Technically correct screening of the bus cable absorbs the electrical interference that can occur in
an industrial environment. You will achieve the best screening results if you adopt the following
measures:
• Hand-tighten the fixing screws of plugs, modules and equipotential bonding conductors.
• Only use plugs with metal or metal-plated housings.
• Connect the screening in the plug over as large an area as possible.
• Connect the screening at both ends of the bus cable
• Do not lay signal and bus cables parallel to power cables (motor leads), but wherever possible in
separate cable conduits.
• In an industrial environment use metallic, earthed cable trays.
• Run signal cables and the associated equipotential bonding conductor as close as possible to
each other, using the shortest route.
• Avoid extending bus cables through the use of connectors.
• Run the bus cables close to existing earthed surfaces.
Important!
In the event of fluctuations in the earth potential, a circulating current may flow through any
screening which may be connected at both ends and connected to the earth potential (PE). In this
case, ensure there is adequate equipotential bonding in accordance with the relevant VDE provi-
sions.
2.5
Bus Termination
If the MOVITRAC
®
31.. frequency inverter is at the beginning or the end of a PROFIBUS segment,
connection to the PROFIBUS network, as a rule, is not via a T bus with an incoming and outgoing
PROFIBUS cable but directly with only one PROFIBUS cable. To avoid interferences on the bus sys-
tem caused by reflections etc., the PROFIBUS segment must be terminated with bus terminating
resistors on the physically first and last stations (
→
Fig. 5).
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
