Adjustment Without Weights - HBM VKIA405 Notice De Montage

12
CAUTION
All unused grommets must be closed off with the blind plugs provided for
the purpose. Tighten the associated swivel nut in each case to stop the
moisture getting in.
A termination resistor that can be actuated in the VKIA405 with a slide switch
is required for problem-free RS 485 communication. If a single VKIA405 is
connected to the control computer, the switch must be set to "On". When
several devices are in the bus, only one switch must be actuated, the others
must be set to "Off". Preferentially, the termination should be activated in the
device that is furthest away in the bus configuration from the control computer.
The control computer interface should also include a bus termination (this is
already integrated in the HBM interface converter 1-SC232/422B).
6

Adjustment without weights

The user characteristic curve can also be calculated if the accuracy
requirements are not high. Application of calibration weights is then not
required. Input is implemented with the commands LDW/LWT, see command
description AD105C. The requirement for this procedure is that transducers of
one type are used and that the following data is known for them:
N = number of transducers
C = sensitivity [mv/V]
n
R = input resistance of transducer [Ω]
LC
The input resistance R
be measured. The value refers to a single transducer and can deviate from
the value of the output resistance. When measuring with an ohmmeter (supply
line blue /black), the transducer must not be connected to the amplifier or
other transducers. If the transducers have different values, a mean value must
be used. In this case, however, it must be expected that the adjustment is less
accurate.
To set the electric sensitivity of the amplifier, the "Span" value must first be
calculated:
= N @ 200 + R
1) R
x
2) Span = C
N
2 mV/V
The initial load (level control with unloaded configuration) is taken into account
by the LDW value. This can be taken over by an identical scale or measured
as follows:
HBM
can be found in the transducer data sheet or must
LC
(Rx is an auxiliary variable without technical significance)
LC
R
LC
1000000
S S
R
X
VKIA405
A2448-1.1 en/de/fr