CMS-660 SYSTEM
CIRCUIT MONITORING SYSTEM (CMS)
21
CMS
BUS
DIGITAL
INPUT
Status
Network
Reset
USB
CMS
BUS
DIGITAL
INPUT
Status
Network
Reset
USB
CMS
BUS
DIGITAL
INPUT
Status
Network
Reset
USB
CMS
BUS
DIGITAL
INPUT
Status
Network
Reset
USB
CMS
BUS
DIGITAL
INPUT
Status
Network
Reset
USB
Modbus RTU
CMS systems
—
Communication to CMS
—
Modbus
Physical Interface RS-485
To communicate with the CMS from an upper system, all devices (masters & slaves) must have the same
data rate and data format.
Physical interface USB
To communicate with the CMS on standard Modbus RTU over serial line, the USB port can be also used.
In this case therefore communication protocol is Modbus RTU via USB CDC RS-232 emulation.
The CMS-660 USB COM port offers the same Modbus map / functions / registers / behavior as
described for the Modbus RTU / RS-485 interface.
The CMS-660 connects as virtual COM port. Please note that the baud rate configured for COM port on
master side is not relevant in this USB mode.
On USB host side every program / app can be used that offers Modbus communication via COM port.
Please check the ABB website to download the latest INF and CAT files, containing all the information to
install the CMS-660 USB driver for Windows.
USB and RS-485 can be used in parallel and independently during operation mode.
Only in configuration mode initiated from one interface it’s not possible to use operation mode from
the other interface.
Control unit’s Modbus ID
You can connect up to 247 control units to one Modbus RTU line. Each control unit must have a unique
Modbus ID (address).
Function Code
• Read operation on registers with access code “R” or “RW” is defined by function 03h “Read Holding
Registers”
• Write operation on registers with access code “W” or “RW” is defined by function 06h “Write Single
Register”
Do not apply functions other than those specified.
Parameter
Values
Default Values
Data rate
2400, 4800, 9600, 19200, 38400, 57600, 115200 Bit/s
19200 Bit/s
Data format
even parity, odd parity, without parity
even parity
