CH Tech EM405D - Manual (Page 17)

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4.0 OPERATING INSTRUCTIONS
4.1 GENERAL
The EM405D is controlled through the Ethernet interface using the TCP/IP protocol to carry a
simple command structure to the module. The carrier contains a set of software controlled
registers that allow the user to request status from the carrier, identify the carrier, and configure
the carrier. All other M/MA controls are dependent on the specific M-module(s) that reside on
the carrier.
4.2 CONFIGURING THE ETHERNET INTERFACE
The Ethernet interface must be properly configured to work on the user’s network. The
flexibility of the EM405D’s Ethernet interface allows it to be used in a large number of possible
network configurations. The unit is delivered with a default configuration that may or may not
be appropriate for the user’s network. It is up to the user and the user’s network administrator to
use the information provided throughout this section to determine what configuration is best for
the given network.
4.2.1 IP Address
The EM405D must have a unique IP address before it can communicate on a network. There are
several options for assigning an IP address to the unit. The option to choose is dependant upon
the type of network for which the EM405D is being configured.
DHCP: The Dynamic Host Control Protocol (DHCP) allows the module to dynamically retrieve
an IP address from a DHCP server at power-up. If DHCP is used, the EM405D may have a
different IP address assigned each time it is powered on or connected to the network. For the
wired EM405D, DHCP is automatically enabled if the IP address is set to 0.0.0.0. For the
wireless EM405D, DHCP is a separate setting. DHCP enabled is the default setting.
AutoIP: The AutoIP protocol allows the module to automatically assign itself an IP address on
networks that do not have a DHCP server. If a DHCP server is not found, the EM405D will
select an IP address from the AutoIP reserved range (168.254.0.1 to 168.254.255.1). The unit
will then send out an address resolution (ARP) request on the network to determine if the chosen
address is already in use. If another device is using the selected IP address then the EM405D
will select another address from the range and repeat the address resolution request. This
continues unit the device finds an IP address that is not in use. For the wired EM405D, manually
setting the IP address to 0.0.0.0 enables AutoIP as well as DHCP and manually setting the IP
address to 0.0.1.0 will disable AutoIP but keep DHCP enabled. For the wireless EM405D both
AutoIP and DHCP have separate enable/disable settings. AutoIP enabled is the default setting.
Static:
For the wired EM405D, manually setting the IP address to something other than 0.0.0.0
will configure the EM405D to use the IP address specified. For the wireless EM405D DHCP
must be disabled and the IP address must be manually set. The configured IP address will
remain static even after power is removed from the module. For proper operation, the IP address
must be chosen according to the network the module is being connected to.