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5. COMMUNICATIONS
5.1. USING THE ANALYSER’S COMMUNICATION PORTS
The T703 is equipped with two serial communication ports, labeled RS232 (male
DB-9 connector) and COM2 (female DB-9 connector), a USB com port and an
Ethernet port located on the rear panel.
The RS232 (COM1) and COM2 ports operate similarly and give the user the
ability to communicate with, issue commands to, and receive data from the
calibrator through an external computer system or terminal.
The RS-232 port (COM1) can also be configured to operate in standard or
RS-232 multidrop mode (Section 5.3).
The COM2 port is configured for standard RS-232 operation by default, but
can be configured for half-duplex RS-485 communication. (Contact the
factory for RS-485 communication configuration).
The COM2 port is disabled for all but Multidrop communications when the
unit is configured for USB communications.
The Ethernet connector allows the instrument to be connected to a network
running TCP/IP or to the public Internet if access is available. The network must
have routers capable of operating at 10Base-T or 100Base-T. DHCP is enabled by
default (Section 5.6.1). This configuration is useful for quickly getting an
instrument up and running on a network. However, for permanent Ethernet
connections, a static IP address should be used (Section 5.6.1.1).
RS-232 DTE AND DCE COMMUNICATION 5.1.1.
RS-232 was developed for allowing communications between data terminal
equipment (DTE) and data communication equipment (DCE). Basic data
terminals always fall into the DTE category whereas modems are always
considered DCE devices.
Electronically, the difference between the DCE & DTE is the pin assignment of
the Data Receive and Data Transmit functions.
DTE devices receive data on pin 2 and transmit data on pin 3.
DCE devices receive data on pin 3 and transmit data on pin 2.
A switch located below the serial ports on the rear panel allows the user to switch
between DTE (for use with data terminals) or DCE (for use with modems). Since
computers can be either DTE or DCE, check your computer to determine which
mode to use. Edit the Instrument and Gateway IP addresses and Subnet Mask to
the desired settings. Then, from the computer, enter the same information through
an application such as HyperTerminal.
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