CAUTION! -. RS485 cabling must be 120Ω
ΩΩ
Ω impedance cable, specified for use with
RS485. 120Ω
ΩΩ
Ω terminating resistors must be fitted to the first and last devices on the bus.
Some PC RS485 cards are already fitted with this resistor, and in this case should not be
fitted externally. If in doubt, consult the supplier of your PC RS485 card.
If the 5510 controller is the ‘last’ device on the bus, then it’s RS485 connection must be
suitably terminated with a 120Ω
ΩΩ
Ω resistor as detailed in the specification laid out in the RS485
standard.
Recommended cable BELDEN 9841 120Ω
ΩΩ
Ω RS485 cable.
DSE part number 016-030.
NOTE: - The RS485 output uses ‘MODBUS’ protocol. It is possible to use third party
software to monitor and control the 5510 module via this protocol.
Please refer to Deep Sea Electronics Plc for details.
16.4.5 MODBUS™
The RS485 output uses Modbus™ communications protocol. This uses a master-slave technique to
communicate. Only the Master can initiate a packet transaction, called a ‘query’. When appropriate
the slave (5510 Module) responds to the query and provides the information requested by the
master.
All supported data can be read and written as specified in the register table (documentation is
available from Deep Sea Electronics Plc.).
When the 5510 Module receives a query it will respond by either supplying the requested register
data or performing the requested action. A slave device (the 5510 module) will never initiate
communications on the Modbus™ link. The 5510 can only be configured as a slave device. The
Master can only query individual slaves. Refer to the Modbus™ protocol document for more details.
Refer to the Link5000plus Manual for further details on communications expansion.
NOTE:- 5560 controller only available with RS485 communications.
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