Explanation of Current Consumption in S800 I/Os
In detailed data of any I/O module it is written like below. What is the meaning of each current consumption in different bus like, +5V Modulebus, +24V Modulebus, or +24V External.
Link for example.
Current consumption +5 V Modulebus 45 mA
Current consumption +24 V Modulebus max 50 mA
Current consumption +24 V external 4 + transmitter current mA, max 260 mA
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I could suggest to read the user manual for S800IO, e.g. 3BSE020923-600 A
There is a limitation of total current consumption for each IO cluster. Separately for +24VDC Modulebus current and +5VDC Modulebus current, which are supplied from the cluster modem trough the Modulebus.
The max. current consumption (+5VDC and +24VDC) depends of the type of the cluster - IO's Directly connected to the CPU, to TB820 or other cluster modem, redundant or not.
So for each IO module type there is a current consumption given, in order to do this check.
Some of the modules require external +24VDC, connected directly to the module, which have to be provided from the external +24VDC power supply.
Source: 3BSE020923-600 A