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Cooper Bussmann 945U-E Wireless Ethernet Modem & Device Server User Manual
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Rev Version 2.14
unit (that is, there is no wireless link), you can configure the digital output to turn On (set) or Off (drop).
Figure 39 Digital I/O
3.14 Modbus I/O Transfer
The 945U-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 945U-E can transfer I/O to
or from almost any combination of Modbus TCP or RTU devices.
The layout of the 945U-E I/O registers is summarized in the table below. Each register is internally saved as a
16 unsigned integer value. A Modbus transaction may access the entire 16-bit value of any register, or 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 and any serial or TCP
connections.
An inverted status of registers 4300–4307 are also available and can be found at register locations 4370–4377.
The status register will contain the value FFFF (hexadecimal) for On and 0000 (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).
4311
TCP-RTU number of connections (RS485).
4312
TCP-RTU Number of Connections (Modbus Server).
4320
On-board digital output value (read/write).
4370
On-board digital input inverted value (read only).
4371
Link status (read only) inverted.
4372
Serial gateway connection status (RS232) inverted.
4373
Serial gateway connection status (RS485) inverted.
4374
TCP-RTU connection status (RS232) inverted.
4375
TCP-RTU connection status (RS485) inverted.
