WI-GTWY-9-xxx Wireless Gateway
Introduction v1.18
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bytes is 2000 (4000/8 + 750*2). The total number of I/O is 3250 which is less than the total limit
of 4300.
1.1.3
Ethernet WI-GTWY-9-ET1
The Ethernet WI-GTWY-9-ET1 provides several different types of Ethernet functionality:
♦
Modbus TCP. Modbus TCP uses Modbus as a base protocol within an Ethernet
communications structure. The WI-GTWY-9-xxx provides class 0, 1 and partially class 2
slave functionality.
♦
EtherNet IP. EtherNet IP is the version of Ethernet used by Allen-Bradley devices. The WI-
GTWY-9-ET1 provides level 2 I/O server CIP (ControlNet and DeviceNet).
♦
Internet functionality. The WI-GTWY-9-ET1 has 1.4Mbyte of non-volatile “flash” memory
for embedded web “pages” (dynamic HTTP), on-board file system, user downloadable web
pages through FTP server, and email functionality (SMTP).
The Ethernet connection is a transformer isolated RJ45 connector, 10/100 Mbit/sec.
The Ethernet WI-GTWY-9-ET1 I/O database has 4300 registers (each of 16 bit value), however
the Ethernet interface only supports 2048 input bytes and maximum 2048 output bytes. Each
byte can be 8 discrete inputs or outputs, but analog or pulse I/O take up 1 byte for low resolution
values (8-bit) or 2 bytes for high resolution values (16-bit).
An “output” is a value coming into the WI-GTWY-9-ET1 via the fieldbus. An input is a value
going out from the WI-GTWY-9-ET1 via the fieldbus.
So an Ethernet WI-GTWY-9-ET1 can handle up to 4300 I/O total, but analog or pulse inputs are
limited to 2048 x 8-bit values or 1024 x 16-bit values. The same limit applies to outputs.
For example, an Ethernet WI-GTWY-9-ET1 can handle 2000 discrete inputs and 500 analog
inputs (assume analogs are 16-bit). The number of input bytes is 1250 (2000/8 + 500*2). The
same unit could handle 4000 discrete outputs and 750 analog outputs. The number of output
bytes is 2000 (4000/8 + 750*2). The total number of I/O is 3250 which is less than the total limit
of 4300.
1.1.4
DeviceNet WI-GTWY-9-DE1
The DeviceNet WI-GTWY-9-DE1 provides DeviceNet 2.0 Slave functionality. DeviceNet is an
automation fieldbus developed by Allen-Bradley (Rockwell Automation).
The DeviceNet connection on the WI-GTWY-9-DE1 is optically isolated RS422 with selectable
baudrate between 125 and 500 Kbit/sec.
The WI-GTWY-9-DE1 I/O database has 4300 registers (each of 16 bit value), however the
DeviceNet interface only supports 512 x 8 bit input bytes and 512 x 8 bit output bytes, and this
limits the amount of I/O that can be transferred via the DeviceNet port.
Each byte can represent 8 discrete inputs or outputs, or an 8-bit value, or two bytes can represent
a 16-bit value. That is, analog or pulse I/O can be transferred as 8-bit registers (1 byte) or 16-bit
registers (2 consecutive bytes).
