The I/O Controllers allow remote control of digital inputs, outputs and a RS232/485 serial port over Ethernet.
Two boxes can be connected to each other thus prolonging the inputs, outputs and serial line over Ethernet (box-to-box mode).

Typical applications

RS-232 connection and 8 + 8 digital I/O signals via Ethernet network
If you need to connect digital signaling (possibly together with RS-232), then I/O Controller is what you need. You can see a block diagram of such a connection (Box-2-Box mode) in the picture below.

Both I/O Controllers are in the TCP Client/Server mode, connection is initialized by the one which needs to transfer new data on it's inputs. If you use the "Keep Connection" function, the connection is held up by sending the NVT NOP (No Operation) packet every 10 seconds. If this packet is not received for longer than 50 seconds, the connection is closed and will be opened again once the network connection is ready. In case of a power failure, you need to define a default state of the output register, which will be set when the power is restored. This state remains unchanged, until the I/O Controller connects to the other side and synchronizes it's outputs with the other side's inputs.

RS-232 and I/O pin control via Ethernet network
This case is similar to the one above, but the I/O Controller sends data to a computer instead of another I/O Controller. You can connect more computers to one I/O Controller, but only one can communicate at a same time. For security reasons it might be useful to define an IP address range which will be accepted by the I/O controller.

Typically you can communicate with a program running on your computer (for testing purposes you can use the "Test mode" in Hercules software) which directly supports NVT communication with digital inputs/outputs.

System Topology

Here you can see a typical I/O Controller system wiring and protocols.

• TCP/IP Server   [Client -> Server]
  The I/O Controller waits as a TCP server until any side (PC or server) opens a TCP connection. When the connection is established, the internal buffered data is sent and then the device allows communication as a standard "terminal server".
  The digital I/O can be controlled over a M2M (Machine to Machine) protocol using the extended RFC2217, but only if NVT support is enabled.
• TCP/IP Client/Server    [Server <- Client]
  The I/O Controller receives serial port data into its internal buffer and tries to send them to the server. It will try to open a connection to the preset IP address and port. If the attempt was unsuccessful, it waits for a second in the TCP Server mode and then tries to open the connection again.
  The digital I/O can be controlled over a M2M (Machine to Machine) protocol using the extended RFC2217, but only if NVT support is enabled.
• UDP/IP
  The data is transferred in UDP packets, with no delivery notification. The device uses a sophisticated "Packetizer", which allows various conditions of what can and what cannot be send from the serial line to Ethernet.
  The remote ethernet I/O (digital inputs and outputs) cannot be controlled in the UDP mode.
• VSP (Virtual Serial Port)
  You have a HW VSP software which creates a virtual COM port under Windows OS, so that the device acts like it's connected directly to your PC, though it's a virtual remote port. If the buffer is enabled and the TCP connection is not available, the data is stored into the internal buffer memory.
  The remote ethernet I/O can be controlled from the HW VSP software in the "Binary I/O", tab, if the NVT support is enabled.

For further information about these products please visit the HW Group web site: www.hw-group.com

Applications
	Remote control of digital I/Os
	Remote COMs over the Ethernet
	UPS control