NOVAR 2100/2200 Operating Manual
5. Computer Controlled Operation
Monitoring the currently measured values and the instrument setup can be done using a remote
computer connected to the instrument via a communication link. Such operation allows you to use all
the setup options of the instrument, which it is not possible from the panel of the instrument.
Following chapters describe instrument communication links from the hardware point of view only and
the webserver function. The detailed description of ENVIS program can be found in the program
manual.
5.1 Communication Interface
5.1.1 Service USB Interface
All of models are equipped with service USB 2.0 interface on the rear panel. You can use this
interface for the instrument setup and actual state checking with a portable PC, especially during
commissioning. For this, appropriate communication cable (USB-A type) is necessary.
The interface is not isolated from instrument internal circuitry and it would not be used for
permanent monitoring – for such purposes use RS-485 or Ethernet interface.
5.1.2 RS-485 Interface (COM)
The link is isolated from other circuits of the instrument. Use terminals
A+
(No. 41),
B-
(42) and
G
(43).
5.1.2.1 Communication Cable
For common applications (cable length up to 100 metres, communication rate up to 9,600 Bd) the
selection of the right cable is not crucial. It is practically possible to use any shielded cable with two
pairs of wires and to connect the shielding with the Protective Earth wire in a single point.
With cable lengths over 100 metres or with communication rates over 20 kilobits per second, it is
convenient to use a special shielded communication cable with twisted pairs and a defined wave
impedance (usually about 100 Ohm).Use one pair for the
A+
and
B-
signals and the second pair for
the
G
signal.
5.1.2.2 Terminating Resistors
The RS-485 interface requires impedance termination of the final nodes by installation of
terminating resistors, especially at high communication rates and long distances. Terminating
resistors are only installed on the final points of the link (for example one on the PC and
another on the remotest instrument). They are connected between terminals
A+
and
B-
.
Typical value of the terminating resistor is 120 Ohm.
5.1.3 Ethernet Interface (ETH)
Using this interface the instruments can be connected directly to the local computer network (LAN).
Instruments with this interface are equipped with a corresponding connector RJ- 45 with eight signals
(in accordance with ISO 8877), a physical layer corresponds to 100 BASE-T.
Type and maximum length of the required cable must respond to IEEE 802.3.
Each instrument must have a different IP- address, preset during the installation. The address can be
set from the instrument panel or you can use the ENVIS-DAQ program. For detection of actual IP-
address you can use
the Locator
function.
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