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COM462RTU_D00010_04_M_XXDE / 06.2021
Modbus process image in the memory of the COM462RTU
6.2
Memory scheme of the process image
6.2.1 BMS device address assignment on the Modbus
As illustrated in the table, the Modbus start address for the respective process image is derived
from the BMS device address. 256 (0x100) Words or 512 bytes are reserved for each BMS device.
They contain all the information requested and transmitted from the bus.
Modbus address ranges of the process images in the memory
BMS
Device
address
Word
HiByte
LoByte
00
…
FF
1
0x
01
Device 1
2
0x
02
Device 2
3
0x
03
Device 3
…
…
…
32
0x
20
Device 32
…
…
…
150
0x
96
Device 150
Tab. 6–1 Modbus start address for each BMS device for which a request is to be sent.
6.2.2 Memory scheme of an individual BMS device
BMS devices feature various types of analogue and/or digital channels. Please take into
consideration that there are device-specific differences:
• BMS devices usually feature 12 channels
• MK800/TM800 supports up to 64 digital channels in the master mode
• The channels 33 to 64 transmit digital messages only
Use the tables on page 35 and page 38 to determine the start address to request the following
device parameters:
• Device type
• Timestamp
• Common alarm
• Device error
• BMS channel
