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245U-E Wireless Ethernet Modem User Manual
53
Rev Version 2.24
3.14 Digital Input/Output
The functionality of the shared Digital Input/Output pin may be configured via the Transfer webpage. As
this pin is shared, the digital input status will be On when the digital output is set to On.
The Digital I/O channel can be transferred to/from another device using Modbus (see “3.15 Modbus I/O
Transfer” below) or it can be configured to provide status of the module communications. If the 245U-E
disassociates from another unit (that is, there is no wireless link), you can configure the digital output to
turn On (set) or Off (drop).
Figure 44 Digital I/O
3.15 Modbus I/O Transfer
The 245U-E provides Modbus TCP client and Modbus TCP server functionality for I/O transfer. The 5000 x
16-bit general purpose registers are provided for Modbus (including the onboard digital input/output) and
are shared for both client and server. Modbus TCP client (master) and Modbus TCP server (slave) are both
supported simultaneously, and when combined with the built-in Modbus TCP to RTU gateway, the 245U-E
can transfer I/O to and from almost any combination of Modbus TCP or RTU devices.
The layout of the 245U-E I/O registers is summarized in the table below. Each register is internally saved as
a 16-bit unsigned integer value. A Modbus transaction may access the entire 16-bit value of any register.
Alternatively, the most significant bit of a register may be accessed as a discrete value. The main use for the
general purpose I/O registers is for intermediate storage, as when transferring I/O from one Modbus slave
device to another. Also provided is the status of the onboard digital I/O, as well as the status of the wireless
link. The 16-bit status register contains the value FFFF (hexadecimal) for On and 0000 (hexadecimal) for Off.
Inverted status registers are also provided where the registers contain 0000 (hexadecimal) for On and FFFF
(hexadecimal) for Off.
Registers
Purpose
1–4299
General purpose I/O registers (read/write).
4300
On-board digital input value (read only).
4301
Link status (read only).
4302
Serial gateway connection status (RS232).
4303
Serial gateway connection status (RS485).
4304
TCP-RTU connection status (RS232).
4305
TCP-RTU connection status (RS485).
4306
TCP-RTU Modbus server connection status.
4307
Multicast pipe connection status.
4310
TCP-RTU number of connections (RS232).