BusWorks Model XT1531‐000
4 CH Current 4 CH Digital I/O w/USB & Modbus
Acromag, Inc. Tel: 248‐295‐0880
‐
22
‐
Device/Communication Setup…
The Internet or world‐wide web is actually a large network made up of many smaller networks (sub‐networks) linked
together by gateways or routers. The gateway or router serves as an access point to/from a particular sub‐network. For
example, your ISP provides DSL modems or cable modems which connect your local hardware to the Internet and often
serve as gateways. The gateway address is the address of this gateway or router in the same subnet as the host, and is
used as the bridge to connect to various other
sub‐networks with different sub‐network addresses and address masks,
that collectively connect together to make up the Internet. Data packets sent over the Internet contain both the
sender’s
Internet address and the receiver’s address. A packet is first s
ent to a gateway computer that understands its own
domain or group of host addresses. The gateway reads the destination address of the packet, and if it is outside of its
own domain, it forwards the packet on to an adjacent gateway that again reads the destination address. Then that
gateway will forward the message on, if the address is not within its domain. Eventually, one gateway recognizes the
packet as belonging to a host within its domain. Finding a match, that gateway forwards the packet directly to the host
whose address is specified. Rather than continually passing a packet from gateway to gateway, some networks will use a
default gateway which is the address of another node on the same network that the software uses when an IP address
does not match any other routes in the routing table (address domain) of the primary gateway.
Ethernet
Setup…continued
An
IP Address
(Internet Protocol Address) is a
unique identification number for any host (this
module) on any TCP/IP network (including the
internet). It uniquely defines one host from all
other computers (hosts) on the Internet. The IP
address is made up of four octets (8 bits), each
octet having a value between 0‐255 (00H‐FFH). It is
expressed here in decimal form, with a period
between octets.
The
Subnet Mask
is used to subdivide the host
portion of the IP address into two or more subnets.
The subnet mask will flag the bits of the IP address
that belong to the network address, and the
remaining bits that correspond to the host/node
portion of the address. The unique subnet to which
an IP address refers to is recovered by performing a
bitwise AND operation between the IP address and
the mask itself, the result being the subnet address.
Gateway Address
refers to the IP Address of the gateway this module is to cross, if your local area network happens to be
isolated or segmented by a gateway. Typically, it is assigned the first host address in the subnet address space. If a
gateway is not present, then this field should contain an unused address within the host subnet address range.
NOTE:
Fortunately, this model uses USB to setup its network configuration parameters, and you can instead change its IP
address to an address compatible with your own PC network without having to network connect to it first. This saves you
from having to consult with your network administrator to either temporarily change your PC’s TCP/IP configuration (see
TCP/IP Properties of Network Configuration in Windows), or perhaps having to create a separate private network using a
second network adapter installed in your PC. The necessary steps would vary with your operating system, but can get
quite involved.
A DNS server relates symbolic names to actual numeric IP addresses, while the DHCP server is responsible for dynamically
passing out IP addresses. The
DNS 1 Address
refers to the IP address of the first Domain Name Server used on this
network. The
DNS 2 Address
refers to the IP address of the secondary Domain Name Server used on this network.
