SMP300 Series • Reference Information 145
The table below shows an example of an invalid class C addressing scheme.
Device IP Address Subnet Mask
Device 1
208.132.180.41
255.255.255.0
Device 2
192.157.180.42
255.255.255.0
Device 3
208.132.180.41
255.255.255.0
Assuming the IP address for device 1 is valid, the IP address for device 2 is invalid because
the network identifier for each address must begin with 208.132.180.xxx. The IP address
for device 3 is invalid because it is using the same IP address as device 1.
The ping command can be used from a computer (see Using the Ping Utility to Test
Communications on page145) or from the web interface to ensure that a device at an
IPaddress is responding correctly.
Using the Ping Utility to Test Communications
Use the ping command to test communications between a Windows‑based computer and
another device on the same network.
1. From the desktop, select Start > Run.
2. The Run dialog box displays. In the Open field, enter ping nnn.nnn.nnn.nnn –t
(where nnn.nnn.nnn.nnn is the IP address of the device to test).
3. Click OK or press the <Enter> key. A window opens showing a series of response
messages (explained below).
4. To stop the ping utility, press <Ctrl + C> on the keyboard.
NOTE: The embedded web page includes a ping utility (see Diagnostic Tools on
page101).
Response Messages
While running the ping utility, a series of response messages are displayed to determine
the status of the communications link. For example, pinging a device with the IP address
208.132.180.48 replies with a message similar to the following:
Reply from 208.132.180.48: bytes=32 time=2ms TTL=32
This is the correct response indicating that the device at the specified address is
communicating correctly. The response time value may vary according to network traffic. If
one of the following messages are received:
• Request timed out — There has been no response from the specified address. Either
the processor is not receiving data (from the computer) or is not sending data back.
Check that the device is powered on and set to the same address that was pinged.
Also, check that the device is correctly connected to the network.
• Reply from 208.132.180.48: Destination host unreachable — The IP address
of the computer is not in the same class as the device being pinged. Check that the
subnet mask on both the computer and the device are set to the same value. Also
check that both IP addresses are within the correct range for the chosen class and
are compatible (see Subnet Mask on page143 and What is an IP Address? on
page142 to select the subnet mask class that matches the IP address class).