23
Product Information on the Manual S7-300 Module Specifications, Edition 11/2002
A5E00213444-02
2.3 Measuring methods and measuring ranges of the SM 331;
AI 8 14 Bit High Speed
Measuring Methods
You can set the following measuring methods for the input channels:
S Voltage measurement
S Current measurement
You perform the setting by means of the measuring range modules on the module
and with the “measuring method” parameter in STEP 7.
Unused Channels
You must short-circuit unused channels and connect them to M
ANA
. In this way,
you obtain an optimum interference immunity for the analog input module. Set the
“measuring method” parameter for unused channels to “disabled”.
Special characteristics of unused channels for some measuring ranges
Since configured inputs can remain unused because of the channel group
generation, you must take note of the following special characteristics of these
inputs to enable the diagnostic functions on the used channels.
S Measuring range 1 to 5 V: parallel connection of the unused input with the
used input of the same channel group.
S Current measurement, 2-wire transmitter:
two channel wiring options.
a) Leave the unused input open and do not enable diagnostics for this
channel group. Otherwise, if diagnostics are enabled, the analog
module triggers a single diagnostic interrupt and the SF LED of the
analog module comes on.
b) Connect the unused input with a resistance of 1.5 to 3.3 kW. You may
then enable diagnostics for this channel group.
S Current measurement 4 to 20 mA, 4-wire transmitter: series connection of
the unused input with the input of the same channel group.
To Next Page
Loading...
