Watlow EM Gateway - Manual (Page 4)

4
Chapter One
Product Overview
The EM00-GATE-0000 is a gateway / bridge that allows up to 32 Watlow controllers to be directly
connected to an Ethernet network. Using an HTTP Browser such as Microsoft Internet Explorer or
Netscape Navigator you may access 16 controllers and view several controllers’ parameters via an
onboard Web (HTTP) server.
Ethernet Gateway
The Ethernet gateway provides a means for monitoring and configuring runtime parameters of multiple
controllers via a web browser. The gateway is also a bridge for Modbus messages between the Ethernet
bus and EIA-485 or EIA-232 links. The Gateway supports full product configuration; monitoring and
configuration of runtime parameters via MODBUS TCP over TCP/IP using a software package such as
Watview sold by Watlow.
Ethernet Gateway Architecture
This product has three physical connectivity points to the physical world. They are the serial (EIA-485 or
EIA-232), Ethernet port (10BaseT), and the power supply pins.
The EIA-485 / EIA-232 connection supports Modbus RTU protocol and operates as a Master port. It will
initiate data read/write requests to supported standard Watlow controllers. There exists a virtual image of
the controller’s data points in the gateway. The polling engine that initiates the Modbus RTU requests is
responsible for synchronization of the virtual image and the actual controller. Changes to control data
occur both at the controller and at the virtual image.
The 10BaseT connection supports the TCP/IP stack. At the application layer it has an HTTP (web) and
Modbus server. The HTTP server will provide current controller status from the virtual image via HTML.
The HTTP server provides a means of changing some runtime parameters via HTML. The TCP/IP stack
supports DHCP client, AutoIP, static IP, DNS client, and Netbios name resolution. The 10BaseT
connector is an RJ45 per the IEEE 802.3 specification.
The EM00-GATE-0000 can be used as a bridge for Modbus RTU messages. This is concurrent with all
other communicating functions. In this scenario, the gateway simply passes the request that comes in on
the Ethernet connection through to the EIA-485 or EIA-232 connection. When the response is returned
from the controller, it is sent back on the Ethernet connection. No processing of the packet contents is
necessary to bridge the two physical layers.
Block Diagram of Gateway
GATEWAY
Poll
Engine
Modbus
TCP/IP
TFTP
Client
Modbus
RTU
E
therNet
PowerSource
RS
-485
Virtual
Image
WEB
Server
TCP/IP