User manual

105G Wireless Gateway User Manual
Elpro_man_105g_1.18.doc Page 14
The 105G I/O database effectively isolates the fieldbus 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 minimizes 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 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 fieldbus 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”. This means that the output register has
priority over the input register - if there is a conflict, the input value is ignored.
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.
♦ Low battery voltage. The 105G has an internal battery charger to trickle charge a back-up
battery. If the battery voltage is low, this status is set.
♦ Battery voltage - the actual value of the connected battery voltage.
1.2.2 I/O Expansion - 105S & 115S modules
The 105G provides eight on-board discrete I/O. Where additional discrete or analog I/O is
required an external expansion I/O modules can be connected to the RS485 port of the 105G
module. See section 4.15 ‘Connecting Serial I/O’ for more details on this.
Note: Serial Expansion modules cannot be connected to the 105G-MD1 unit (as this unit uses
the RS485 port for Modbus or DF1 communications), unless this unit is configured as
“Repeater-only” and does not have a host device connected.
The 115S modules can communicate in the same function as a 105S module using the WIB-net
Protocol or via Modbus RTU protocol. The 115S can act as a Modbus Slave device with a Modbus
RTU address range of 1-99, which is selectable via the rotary switches on end plate of module.
If using a 105G-MD1 utilising Modbus Protocol and additional I/O is required then the 115S
module can be added via RS485 communications onto the Modbus network with a unique
Modbus RTU address.