How to Connect to Acromag Ethernet I/O Devices Application Note

Getting Connected to Acromag Ethernet I/O Devices

Acromag 900EN

These instructions summarize the basic steps you will have to take in order to initially connect an Acromag Ethernet I/O product to your Personal Computer (PC) or laptop.

To connect an Ethernet device to your PC, consult with your network administrator and either temporarily change the TCP/IP configuration of your existing network adapter (see TCP/IP Properties of Network Configuration in Windows), or create a separate private network using a second network adapter installed in your PC (recommended). The necessary steps to accomplish this will vary with your operating system, but are outlined below for Windows® based computers.

NOTE: You must have a PC with at least one Network Interface Card (NIC) installed.

• IP Address is the default factory IP address setting of all Acromag Ethernet I/O devices. It is also the address that Acromag devices assume when placed in their default communication mode.
• You must set the IP address of your network interface to an address of 128.1.1.x, where x is any integer from 1 to 254, except 100, in order to initially communicate with Acromag Ethernet I/O products.

If your PC is already connected to a network, it is preferable to have a second Network Interface Card (NIC) installed. If you connect to your own network via a wireless connection, then you probably have an unused NIC connection on your PC that you can use to connect to the Acromag product. Either scenario will allow you to maintain uninterrupted connection with your own network, while creating a separate private network for communicating directly with your Acromag Ethernet product. If you only have one NIC installed and no wireless adapter, then you will temporarily lose connection with your own network when you change the IP address of your adapter to an address within the default address domain of the Acromag device.

Why can’t you initially connect the Acromag product directly to your own network?

Every Ethernet network device (including the NIC installed in your PC) must have its own unique IP address in order to differentiate itself from the other devices on the network. The IP address not only identifies the device on the network, but it also determines which other devices may communicate with it. Acromag Ethernet devices have a default IP address setting that defines an address domain that is likely outside of your own. This will prevent you from simply connecting our device to your network to begin communicating with it. However, once you establish initial communication, you can change the units IP address setting to a value compatible with your own network.

Acromag devices use a default IP address of and a subnet mask of This setting is also used for Acromag devices sent to their default communication mode. These settings define a Class C sub network address for the device, and only IP addresses with a prefix of “128.1.1” and a suffix from 1 to 254, except 100, can communicate with it. Once you establish initial communication with an Acromag device, you can easily change its IP address setting to something compatible with your own network.


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