ABB AC 800F

4 Cabling the AC 800F
4-65
Features of the Redundancy Link Module RLM 01:
• Conversion: line M lines A/B
• For use on Profibus DP/FMS lines
• Automatic line selection
• Transmission rate 9.6 kbauds .... 12 Mbauds
• Communication monitoring
• Repeater functionality
• Redundant power supply
• Power supply monitoring
• Functional electrical isolation of the three serial
RS485 interfaces from each other and from the
power supply.
• Status and error indicators
• Potential-free alarm contact
• Easy mounting on DIN rails
Functional description of RLM 01
The three RS485 interfaces of the RLM 01 module support all transmission rates from
9.6 kbits/s to 12 Mbits/s, as specified in DIN 19254/EN 50170 for Profibus DP/FMS.
The RLM 01 module has a repeater functionality, i.e. the signal shape and amplitude
are recovered if required. All three Profibus lines A, B and M are permanently
monitored for proper activities and error occurrence. Detected errors are indicated by
LEDs on the RLM 01 front panel and, in parallel, through a potential-free alarm
contact.
The data packages received via line A or B are checked for the correct telegram
header and then further transmitted to the M port. The data package arriving first has
priority over the other one. If the data packages should arrive at the same time, one of
them is chosen randomly. The first character of each data package is used for
checking and selection. If the control logic recognizes an incorrect telegram header on
line A, it automatically switches over to line B, and vice versa.
Data packages arriving on line M and which have a correct telegram header are
transmitted in parallel to the A and B ports. The data packages are checked by their
first character. If the telegram header is incorrect, the data package is not output to
lines A and B.