Page 40 of 52
13.5.
External RS-485 devices
Problem
Possible cause(s)
Possible solution(s)
READ ERROR shown on
I/O
Status
screen
External device address incorrect
Check configured address is
correct. This setting can usually
be changed on the external
device using DIP switches or
config software.
Two external devices connected
on the bus with the same address
Change the address on the
conflicting device
External device communication
settings incorrect
Check configured baud rate and
parity settings are correct. These
settings can usually be changed
in the external device using DIP
switches or config software.
Polarity of ‘A’ and ‘B’ connections
incorrect
Check polarity is correct.
Note: The labelling of ‘A’ and ‘B’
can be ambiguous so try
swapping 'A' and 'B' even if this
means going against connection
diagrams
No ground connection
Ensure there is a ground
connection between
MelcoREMOTE and external
device
RS-485 termination / pullup /
pulldown resistors are set
incorrectly
See the Connecting to external
devices section for more
information.
Too many RS-485 devices
connected on the bus
If there are more than 32 devices
connected on the bus then an RS-
485 repeater may be needed to
boost the bus signal. These can
be purchased from many different
electronics retailers.
External device register attempted
to be read is invalid
Check register numbers against
external device documentation.
WRITE ERROR shown on
I/O
Status
screen
Value being written is out of range
Check value is within range by
referring to device documentation
Summary of Contents for MelcoREMOTE
Page 2: ...Page 2 of 52 ...
Page 7: ...Page 7 of 52 Fig 2 Overview I 2 ...
Page 46: ...Page 46 of 52 RS 485 Expansion Devices Address Description ...
Page 47: ...Page 47 of 52 Centralised Controllers Modbus TCP Devices IP Address Description ...
Page 50: ...Page 50 of 52 ...
Page 51: ...Page 51 of 52 ...
