MODBUS communication
10.3 MODBUS functions
3KC ATC6500 transfer control device
186
Manual, 05/2019, L1V30538268002A-01
T1,T2,T3: Corresponds to the time during which the data may not be exchanged via the
communication bus. The connected devices use this to detect the end of one command and
the beginning of a new one. This time must be at least 3.5 times longer than the time
required for sending one character.
Note
The ATC6500 measures the time between receiving one character and receiving a new one.
If this value exceeds the time required for transmitting 3.5 characters at the selected baud
rate, then the next character is regarded as part of a new message.
Example:
In order, for example, to read out the number of alarms when changing over to breaker 1
(BRK1) (Register: 3Ah), the following command must be sent:
01
04
00
39
00
02
A1
C6
01 = Slave address
04 = MODBUS function 04 Read Input Register
00 39 = Register address of the query (number of alarms for the changeover to Breaker 1 (BRK1)); reduced by 1 (see
chapter Data library)
00 02 = Number of registers to be read, starting at Address
22 A1 C6 = CRC Checksum
The following reply is sent by the ATC6500:
01
04
04
00
00
00
07
BA
46
01 = ATC address (Slave 01)
04 = Function requested by the master
04 = Number of bytes that the ATC sends
00 00 00 07 = Hexadecimal value for the alarms when changing over to Breaker 1 (BRK1) = 07
BA 46 = CRC checksum
10.3
MODBUS functions
The following MODBUS functions can be performed with the ATC6500:
03 = Read input register
Allows parameters of the ATC to be read.
04 = Read input register
Allows parameters of the ATC to be read.
06 = Preset single register
Allows parameters of the ATC to be rewritten.
07 = Read exception
Allows the status of the ATC to be viewed.
10 = Preset multiple register
Allows some parameters of the ATC to be rewritten.
17 = Report slave ID
Allows information about the ATC to be read out.
