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E5805A USB/RS232 Interface
can be connected to a bus- powered hub, which obtains power from its upstream host and provides up to 100 mA for each downstream port.
Due to the limited available power for bus- powered hubs, cascading two bus- powered hubs is an illegal topology, and devices connected to the second hub will not function. USB specifications limit the connection of a bus- powered hub to a self- powered hub or host only.
According to the USB Specification, the maximum limit of hubs cascaded in series cannot exceed five. In other words, you may have a maximum of five hubs between any device and the host. This does not mean that the maximum number of hubs in a system is five. Indeed, up to seven hubs can be connected parallel at any given level. You must tally both external and embedded hubs when counting downstream hubs.
The E5805A is a
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