61
115895B System Installation Manual
MODBUS SERIAL COMMUNICATION OPTION SECTION
SECTION 5
Biasing, Link Load and Link Termination
The MODBUS Communication Option Board includes weak (10k
Ω) pull-up
and pull-down resistors on the MODBUS RS-485 link for the purpose of link
biasing. Therefore, external link biasing on the bus is not required when at least
one MODBUS Communication Option Board is connected on the bus segment.
The RS-485 transceiver in the MODBUS Communication Option Board is
a Maxim MAX487E, which presents a quarter (1/4) Unit Load on the bus. Up to
128 quarter-Unit-Load devices may be on the same bus segment before
requiring a repeater. However, for long (1000ft and greater) RS485 wire runs,
fewer devices and lower baud rates (9,600 bps or 19,200 bps) are recommended
for reliable performance. If this is not possible, you should consider multiple
independent MODBUS segments, either running separately as separate
systems, or combined with signal repeaters, or combined over MODBUS TCP
using an Ethernet backbone and bridge devices.
The MODBUS electrical specification allows various wiring topologies, but
for best performance at high baud rates and long wire runs, pure daisy chaining
is strongly recommended to minimize reflections on the line.
To further minimize reflections and improve link reliability, you must
correctly terminate the MODBUS link externally on either end of the bus as
recommended by the MODBUS specification (and according to the type of link
cable used).
SECTION 6
Device Identification
To enable identification and differentiation of
MODBUS Communication
Option Boards on the same MODBUS link, the board:
•
Allows you to set a custom User ID string (up to 31 bytes of printable
ASCII characters, i.e. ASCII characters 0x20 through 0x7E)
•
Allows you to read out identification strings using either of two different
methods:
o
MODBUS Report Server ID (MODBUS Function Code 0x11)
o
MODBUS Encapsulated Interface Transport
‘Read Device
Identification
’ (MODBUS Function Code 0x2B / 0x0E)
The identification strings that you can read out include the User ID string
(if set), manufacturer info, model number, and firmware revision.
Summary of Contents for Illuminator Supernova Series
Page 16: ...15 115895B System Installation Manual Figure 5 2 AC Connections for 6 25 k W 7 5 kW systems ...
Page 17: ...16 115895B System Installation Manual Figure 5 3 AC Connections for 10 kW 16 7 kW systems ...
Page 30: ...115895B System Installation Manual PART II OPTIONS MANUALS Section continues on next page ...
Page 95: ...94 115895B System Installation Manual SERIAL TO ETHERNET ADAPTER OPTION SECTION ...
Page 96: ...95 115895B System Installation Manual SERIAL TO ETHERNET ADAPTER OPTION SECTION ...
Page 114: ...113 115895B System Installation Manual DRAWINGS SECTION ...
Page 115: ...114 115895B System Installation Manual DRAWINGS SECTION ...
Page 116: ...115 115895B System Installation Manual DRAWINGS SECTION ...
Page 117: ...116 115895B System Installation Manual DRAWINGS SECTION ...
Page 118: ...117 115895B System Installation Manual DRAWINGS SECTION ...
Page 119: ...118 115895B System Installation Manual DRAWINGS SECTION ...
Page 120: ...119 115895B System Installation Manual DRAWINGS SECTION ...
Page 121: ...120 115895B System Installation Manual DRAWINGS SECTION ...
Page 122: ...121 115895B System Installation Manual DRAWINGS SECTION ...
Page 123: ...122 115895B System Installation Manual DRAWINGS SECTION ...
Page 124: ...123 115895B System Installation Manual DRAWINGS SECTION ...
Page 125: ...124 115895B System Installation Manual DRAWINGS SECTION ...
Page 126: ...125 115895B System Installation Manual DRAWINGS SECTION ...
Page 127: ...126 115895B System Installation Manual DRAWINGS SECTION ...
Page 128: ...127 115895B System Installation Manual DRAWINGS SECTION ...
Page 129: ...128 115895B System Installation Manual DRAWINGS SECTION ...
Page 130: ...129 115895B System Installation Manual DRAWINGS SECTION ...
Page 131: ...130 115895B System Installation Manual Notes ...