Rs 232 Interface : Characteristics; Use / Procedure; Making A Measurement; Connections - Chauvin Arnoux C.A 6250 Manual De Instrucciones

2.4

RS 232 INTERFACE : CHARACTERISTICS

The RS 232 jack can be used with 4 different peripherals (choice of 4 different links in SET-UP):
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- PC: activate RS232 link between the instrument and a computer
- PRNT: activate RS232 link between the instrument and a printer
- TRIG: activate the remote measurement triggering function
- VT100: activate RS232 link between the instrument and a display console
Note that the RS232 can be switched OFF to deactivate the input and output functions of the connector
(saves battery power).
Selecting an RS232 link opens a submenu in which to choose the data rate between the instrument and
the peripheral. This adjustment is made in SET-UP (see § 3.6)
The baud rate can be set to 4,800, 9,600, 19,200, or 31,250.
Data format: 8 data bits, no parity, 1 stop bit, hardware control (CTS)
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3.1

MAKING A MEASUREMENT

3.1.1 Connections

Connections are made in accordance with the 4-wire measurement principle; the set-up used is shown
in the figure bellow :
From a DC voltage U, a generator delivers a current I.
A voltmeter measures the voltage drop Ux on the terminals of the resistance Rx to be measured and
displays Rx = Ux/I.
The result is independent of the other resistances in the current loop (Ri, Rf, Rc) provided that the total
voltage drop they cause, in combination with Rx, is less than the voltage the source can deliver,
U (U = 6V).

3.1.2 Sequence of use

1. Turn the rotary switch from OFF to the desired range. The range and the associated measuring
current are then indicated at bottom left in the display unit.
2. Press the key until the desired measurement mode is obtained.
For a detailed description of the different measurement modes, see § 3.2.
3. If desired, press the R(θ) key to activate the temperature compensation function. For a detailed
description of this function, see § 3.3.

3. USE / PROCEDURE

Where:
Ri = Internal resistance of the instrument.
Rf = Resistance of the measuring wires.
Rc = Contact resistance.
Rx = Resistance to be measured.
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