JUMO 902930 Wtrans Transmitter RTD Temperature Probe with Wireless Data Transmission Operating Manual - Manual (Page 27)

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4 Probe range
Figure 9: Collisions depending on the number of probes
at a transmission interval of 1 s
As the figure shows 9, the error curve increases sharply once 24 probes are reached.
For this reason, we recommend using a maximum of 16 probes for the smallest transmission
interval of 1 s. For the factory setting of 10 s, a considerably larger number of probes is possi-
ble.
Estimation of the maximum number of probes
If more than the recommended 16 probes are to be used at a transmission interval of 1 s, select
a higher transmission interval to prevent an increased error quota.
Example:
When the number of probes is to be increased additionally, the following calculation results in
the next example:
Example:
However, from a transmission interval of ≥ 3 s, the telegram is transmitted twice. For this rea-
son, the number of probes to be used is cut in half.
The identical behavior occurs from a transmission interval of ≥ 60 s. From this transmission
interval, the telegram is transmitted three times.
External probes
The ISM band can also be used freely by other devices. External probes can transmit on the
same frequency. If, for example, the probe and an external probe transmit their radio telegrams
at the same time, the telegrams are destroyed. Due to the fact, that the probes are not able to
check their own active transmission, no error is detected.
Electrical devices
In a rough industrial environment, radio telegrams can be destroyed, for example, by frequency
converters, electrical welding equipment or poorly shielded PCs, audio/video devices, electron-
ic transformers, electronic ballasts, etc.
16 18 20 22 24 26 28 30
Number of probes
Fault incr
ease
16 transmitters with a transmission interval of 1 s = 32 transmitters with a transmission interval of 2 s
16 transmitters with a transmission interval of 1 s = 48 transmitters with a transmission interval of 3 s
(in theory)
16 transmitters with a transmission interval of 1 s = 24 transmitters with a transmission interval of 3 s
(effective)