HMS Anybus CompactCom B40 Modbus Serial User Manual page 11

Modbus Application Interface
6. Set the size of the Read Process Data area to register 0x5103. Data type (byte or word) is
configured with register 0x5100.
Example – Using the Modbus function Write Single Holding Register to configure
Read Process Data size 18 bytes. Assuming default value of register 0x5100, i.e. data type is
UINT8.
Address
0x05
7. The CompactCom is now ready to start communicating with the network master with the
configured settings. Start cyclical read/write of process data to register 0x0000- and 0x1000-.
Also consider to cyclically monitor the values of register 0x0FFD (Anybus Switch Status),
0x0FFE (LED status), and 0x0FFF (Anybus Status).
If a reset request is indicated in the Anybus Status register, the host application must reset
the CompactCom, and start the initialization sequence from step 1. See
p. 18.
Example – The Modbus function Read/Write Multiple Registers allows you to
both read and write registers with one command. In this example the status registers and
the read process data registers are read, at the same time as the write process data
registers are written.
Command:
Address
0x05
Response:
Address
0x05
The Anybus CompactCom will stay in state SETUP until values have been written to 0x5102 and
0x5103 (items no. 5 and 6 in the list above). The Anybus CompactCom will then change states to
WAIT_PROCESS, and the registers 0x5100-0x5103 will be read-only.
See also ..
• The Anybus State Machine, p. 42
Anybus ® CompactCom ™ B40 Modbus Serial User Manual
Data
Function Code
Register Address
6 0x5103
Function Code Data
Read Quantity
Starting to Read
Address
23 0x0FFD 12
Function Code Data
Read Byte Count
23 24
Register Value
18
Write Quantity Write
Starting to Write Byte
Address Count
0x0000 10 20
Read Reg Values
24 bytes of data
9 (48)
CRC
CRC-16-ANSI
RESET (Reset Input),
CRC
Write
Reg
Values
20 bytes CRC-16-ANSI
of data
CRC
CRC-16-ANSI
SCM-1202-130 1.1 en-US