ABB AC500 PLC - Cable Lengths; Bus Termination (RS-485 only); 1.3.3.3 State LEDs

Bus line
Remarks Commonly used telephone cables with PE insulation and a
core diameter of > 0.8 mm are usually sufficient.
Cables with PVC core insulation and core diameter of
0.8 mm can be used up to a length of approx. 250 m. In this
case, the bus terminating resistor is approx. 100 Ω.
Cable Lengths
The maximum possible cable length of a serial connection subnet within a segment depends on
the baud rate (transmission rate).
RS-232 (for point-to-point connection):
Baud rate Maximum cable length
9.6 kBaud to 187.5 kBaud On request
RS-485 (for point-to-point or bus connection):
Baud rate Maximum cable length
9.6 kBaud to 187.5 kBaud On request
Bus Termination (RS-485 only)
The line ends of the bus segment must be equipped with bus termination resistors. Normally,
these resistors are integrated in the interface connectors.
Master at the bus line end,
pull-up and pull-down activated,
bus termination 120 Ohms
Slave within
the bus line
Slave at the bus line end,
bus termination 120 Ohms
1
2
3
4
RxD/TxD-P
RxD/TxD-N
1
2
3
4
1
2
3
4
120
Ohms
120
Ohms
Term. P
Term. N
1.3.3.3 State LEDs
LED Color State Description
PWR Green ON (light) Voltage is present
OFF (dark) Voltage is missing
RDY Yellow Programmable Depends on user program
RUN Green Programmable Depends on user program
STA Yellow Programmable Depends on user program
ERR Red Programmable Depends on user program
Device Specifications
Communication Modules (AC500 Standard) > CM574-RS with 2 Serial Interfaces
2019/04/173ADR010121, 13, en_US102