4.2.7.2 RS485 SERIAL PORT
This section is included to give information about the currently selected serial port
The items displayed on this page change depending upon configuration of the module. Refer to the
system supplier for further details.
NOTE: Factory Default settings are for the RS485 port to operate at 19200 baud, MODBUS
slave address 10.
Connected to an R485 MODBUS Master
The modules operate as a MODBUS RTU slave device.
In a MODBUS system, there is only one Master, typically a
PLC, HMI system or PC SCADA system.
This master requests for information from the MODBUS slave
(The module) and may (in control systems) also send request
to change operating modes etc. Unless the Master makes a request, the slave is ‘quiet’ on the data
link.
The factory settings are for the module to
communicate at 115200 baud, MODBUS
slave address 10.
‘Master inactivity timeout’ should be set to
at least twice the value of the system scan
time. For example if a MODBUS master
PLC requests data from the module once
per second, the timeout should be set to
at least 2 seconds.
The DSE MODBUS document containing register mappings inside the DSE module is available upon
request from support@deepseaplc.com. Email the request along with the serial number of the DSE
module to ensure the correct information is sent.
Typical Requests (Using Pseudo Code)
MainsFrequency=ReadRegister(10,0423,1): reads register (hex) 0423 as a single register (mains
frequency) from slave address 10.
WriteRegister(10,1008,2,35701, 65535-35701): Puts the module into AUTO mode by writing to
(hex) register 1008, the values 35701 (auto mode) and register 1009 the value 65535-35701 (the
bitwise opposite of auto mode)
Warning=(ReadRegister(10,0306,1) >> 11) & 1): reads (hex) 0306 and looks at bit 12 (Warning
alarm present)
ElectricalTrip=(ReadRegister(10,0306,1) >> 10) & 1): reads (hex) 0306 and looks at bit 11
(Electrical Trip alarm present)
ControlMode=ReadRegister(10,0304,2): reads (hex) register 0304 (control mode).
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