Measurement Specialties 9116 - Manual (Page 19)

Pressure Systems, Inc. Model 9116 User’s Manual
Page 10 www.PressureSystems.com
The host and each module must have a unique Ethernet Hardware Address (a.k.a. MAC
Address) and a unique IP Address. The Ethernet Hardware address is generally fixed (at
manufacturing time of the Ethernet microprocessor board inside the module). The Ethernet
Hardware address is shown on each module’s label. The Ethernet Intelligent Pressure
Scanners are capable of supporting various methods for IP address assignment, using either
the factory default (static IP addressing) or user-configured Static IP addressing or Dynamic IP
address assignment. Dynamic IP address assignment is through the use of RARP or BOOTP
protocols. Unless your application requires the use of Dynamic IP address assignments, it is
strongly suggested that the module be left configured for the Static IP address protocol. This
default method is typically the simplest method for using the Intelligent Pressure
Scanner.
In the Static IP addressing mode, the module will use a factory default IP address on power-up.
This default address is set to 200.20x.yyy.zzz where x is derived from the module type (0 for
Model 9116 and 1 for 9021/9022) and yyy.zzz is derived from the module serial number. A
similar method is used to calculate each module’s Ethernet hardware address shown on the
module tag. Note that each of these fields (separated by a period, ‘.’) is a decimal
representation of a byte value. This means that each field may have a maximum value of 255.
For Model 9116 modules, the default IP address will be 200.200.y.zzz where y and zzz are
calculated as follows:
y is the integer result of dividing the module serial number by 256.
zzz is the remainder of dividing the serial number by 256 (serial number modulus 256).
These calculations may be verified by checking that y * 256 + zzz equals the original module
serial number. Once a module has powered-up and has assigned itself a default IP address, it
is capable of communications.
An alternate method for assigning an IP address to an Ethernet module is referred to as a
Dynamic IP assignment. This method allows a module to have its IP address dynamically
assigned at power-up by an application running on a node of the TCP/IP or UDP/IP network.
When configured for Dynamic IP address assignment protocols, the reset module will broadcast
its Ethernet hardware (MAC) address on the network in a Dynamic IP request packet. This
broadcast packet identifies the module by its hardware address and requests that a dynamic IP
server application return to it an IP address for use. Once this broadcast message is received,
the dynamic server application will then return an IP address to the module in a dynamic IP
reply packet. Most dynamic IP server applications determine this IP address from a user
maintained file that lists Ethernet hardware addresses with their desired IP address. If modules
are added to the network or module IP addresses are to be changed, the user can simply edit
this configuration file. This capability is common on most UNIX based machines and is also
available (although less common) in some TCP/IP packages available for PC platforms.
Support of the Dynamic IP server protocol is not currently included in the Windows
® 95/98/XP or
Windows ® NT operating systems. In order to allow users of PC platforms to make use of the
Dynamic IP capabilities of the Model 9116, a simple Windows ® 95/98/XP/NT application was
developed by Pressure Systems which is capable of acting as a Dynamic IP server. This
application is referred to as BOOTP Lite since it actually makes use of the BOOTP protocol that
closely resembles the Dynamic IP request. Like traditional dynamic IP servers, this application
allows the user to configure a file that contains Ethernet hardware addresses and the
corresponding IP address to assign to those devices. This application is free of charge and
capable of running as a background program on Windows
® 95/98 and NT machines. It may be
downloaded from the PSI home page, www.PressureSystems.com.