JUMO Wtrans p Betriebsanleitung Seite 67

Figure 3:
As figure 3 shows, the error curve increases sharply once there are 24 transmitters.
For this reason, we recommend using a maximum of 16 transmitters for a transmission interval
of 1 s. Selecting a larger transmission interval allows for a significantly larger number of trans-
mitters.
Estimating the maximum number of transmitters
If more than the recommended 16 transmitters are to be used with a transmission interval of
1 s, select a higher transmission interval to prevent an increased error quota.
Example:
16 transmitters with a transmission interval of 1 s = 32 transmitters with a transmission interval of 2 s
The calculation displayed in the next example applies when the number of transmitters is to be
increased further.
Example:
16 transmitters with a transmission interval of 1 s = 48 transmitters with a transmission interval of 3 s
(in theory)
However, as from a transmission interval of ≥ 3 s, the wireless telegram is transmitted twice.
This means the number of transmitters that can be used is cut in half.
16 transmitters with a transmission interval of 1 s = 24 transmitters with a transmission interval of 3 s
(effective)
The same occurs with a transmission interval of ≥ 60 s. As of this transmission interval the wire-
less telegram is transmitted three times.
External transmitters
External transmitters may transmit on the same radio frequency. If, for example, the transmitter
and an external transmitter transmit their wireless telegrams at the same time, the wireless tele-
gram is destroyed. No error is detected because the transmitters cannot check their own trans-
mission while transmitting.
Electrical devices
In a harsh industrial environment, wireless telegrams can be destroyed, for example, by fre-
quency converters, electrical welding equipment, poorly-shielded laptops/PCs, audio/video de-
vices, electronic transformers, electronic ballasts, etc.
16
Collisions depending on the number of transmitters
with a transmission interval of 1 s
18 20 22 24
Number of probes
4 Transmitter range
26 28 30
25