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8.1.3
BMS master
A master can query all measured values, alarm and operating messages from a slave. If bus
address 1 is assigned to a device, this device automatically operates as master, i.e. all
addresses between 1 and 150 are cyclically scanned for alarm and operating messages via
the BMS bus. If the master detects incorrect answers from a slave, the fault message "Fault
RS-485" will be output via the BMS bus.
The following fault causes may exist:
•
Addresses are assigned twice
•
A second master exists on the BMS bus
•
Interference signals occur on the bus lines
•
A defective device is connected to the bus
•
Terminating resistors are not activated or connected
8.1.4
Commissioning of an RS-485 network with BMS protocol
•
Interconnect terminals A and B of all bus devices in one line.
•
Switch the terminating resistors on at the start and the end of the RS-485 network. If a
device at the end of the bus is not terminated, connect a 120 Ω resistor to terminals A
and B.
•
Switch the supply voltage on.
•
Assign the master function and address 1 to a bus-capable device.
•
Assign addresses (2...90) to all other bus devices in consecutive order.
8.1.5
Address setting and termination
Correct address setting and termination is essential for proper functioning of the
isoxx1685xx-xxx series insulation monitoring device.
CAUTION
•
Ensure correct address setting and termination of the device!
36
Risk of bus errors!
Double assignment of addresses on the respective BMS busses can cause
serious malfunctions.
Device communication
isoPV1685xxx_D00007_08_M_XXEN/03.2023
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