sources and causes of these interferences (before switching to multi-channel mode and
averaging mode, when it is more difficult to understand the sources of interference).
7.
When using ("by default") in the multi-channel operation mode of the maximum
switching frequency (2 MHz)
,
the output impedance
of the E-502
signal circuit
must
be from 0 to 50 Ω (in the frequency band up to 10 MHz), and this voltage source
must be connected to connector E-502 by wires of zero length.
This is achieved
either by directly connecting the output of the signal source itself (50 Ω) or by
connectin
g its load resistor (up to 50 Ω) directly to the cable part of the E
-502 signal
connector (cases of connecting a 50 Ω coherent line or a current shunt to 50 Ω of the
external current measurement circuit).
8. When using a multichannel mode of non-zero length of wires to the voltage source
and (or) with an output resistance of the signal circuit of more than 50 ohms, the
program setting of the signal conditioning time n
su
> 1 (s
) should be applied.
9.
In multi-channel mode, the optimal settling time n
su
(s.
) should be selected
depending on the output impedance of the signal source, the length and the
coherence of the cable.
It is suggested to choose the optimal
n
su
for this channel by the
criterion of obtaining a small inter-channel signal transmission from the previous polling
channel.
10.
To improve the signal-to-noise ratio and increase the resolution in the
measurement path, it is recommended to use the maximum possible averaging
factor n
av
> 1 (s.
for the required channel polling frequency and the necessary
signal conditioning time n
su
.
11. Do not exceed the operating voltage ranges at the inputs X, Y, GND32 (s.
12. Use the E-502 "with common ground" operation mode only in case of closely located
low-resistance signal sources. Optimizing the
n
su
and n
av
settings for the "common
ground" mode is required. Do not make "common ground" connections through the
cable, if there are no low-resistance pull-up resistors on the E-502 side.
13. When connecting the E-502 "with common ground", the GND32 circuit must be in the
same group of cable wires (in particular, within the same shield) as the other X and Y
circuits operating on the "common ground" scheme.
14. When using 16 to 31 channels, it is advisable to combine E-502 "differential" and
"common ground" connections and settings to obtain more channels operating in
differential mode. In this case, the wires X and Y (differential circuit) and the wires X,
Y, GND32 ("common ground" circuits) should form different groups in the cable in a
common AGND circuit situation for these groups.
15. Do not allow through-currents on the shields and common wires of analog and digital
signal circuits. Consider the internal circuit for connecting the common wires of the
signal circuits to E-502 (p.
4.8.
Calculation of total load power of E-502 output circuits
If you intend to use E-502 output circuits to connect any external loads, then the total load
power should not exceed the power specified in the specification (paragraph
on page
. The
load power should be estimated according to the procedure described below.
Total load power , taken from the supply system E-502, is:
