Chapter One
Introduction
MAN_105G_1.5
Page
10
status registers. There are also other registers in the database that can be used for system
management - they are discussed later in this manual.
•
The radio port allows the 105G to
communicate with other 105G
and/or 105U modules using the
105U protocol (called “ELPRO
105U”). Messages from the 105U
modules are received by the radio
port and used to update the input
values in the 105G database. The
radio port also creates the correct
radio message to set outputs on the
remote 105U modules.
The ELPRO 105U protocol is an
extremely efficient protocol for
radio communications. Radio
messages can be sent using exception reporting - that is, when there is a change of an
input signal - or by read/write messages. Each message can comprise a single I/O value,
or multiple I/O values (termed a “block” of I/O). There are also update messages, which
are sent for integrity purposes. Messages include error checking, with the destination
address sending a return acknowledgement. Up to five attempts are made to transmit the
message if an acknowledgement is not received. The ELPRO 105U protocol is designed to
provide reliable radio communications on an open licence-free radio channel.
•
The Data-Bus port enables communications between a host device, which could be a PLC,
DCS, HMI, intelligent transducer, or an actual data-bus), and the 105G database. A “host
device” may be several devices connected to a data-bus (for example, an Ethernet LAN) -
in this manual, the LAN is considered as a “host device”.
The data-bus port decodes messages from the host device and reads or writes I/O values to the
database. The data-bus port can also generate messages to the host device.
The 105G database effectively isolates the data-bus and the radio network. This provides a
high level of system performance. The 105U radio protocol is very efficient and reliable for
radio communications. It minimises radio channel usage by "change-of-state" reporting, and
allows the use of intermediate repeater addresses. It also allows peer-to-peer (105U to 105U,
105G to 105G) and peer-to-master (105U to 105G) communications. PLC protocols, by
comparison, are designed to provide transfer of large I/O files by "wire" link. The 105G
retains the advantage of both protocols in their respective communications media.
1.2.1
On-board I/O
The 105G has eight on-board discrete I/O. Each I/O point can be used as either a discrete
input (voltage free contact input) or discrete output (transistor output) - an I/O point cannot
be used as both input and output. Each I/O point is linked to two separate registers I/O
registers in the database - one for the “input” function and one for the “output” function.. If
the output register is set “on” by the data bus or by a radio message from a remote module,
then the 105G will automatically set the input register for the same I/O point to “off”.
The 105G also has three internal inputs linked to I/O registers:
♦
Supply voltage status - if the normal supply fails, this status is set on.
DATA BUS
INTERFACE
DATA BUS
PROFIBUS
ETHERNET
MODBUS
DFI
RADIO
PORT
I/O
DATABASE
905U
RADIO
INTERFACE
105U-G
ON-BOARD I/O
EIGHT DISCRETE I/O SIGNALS
