SRP-F310/312
※Note: Minimum conductor construction must be stranded tinned copper.
To minimize end user termination problems, USB uses a keyed connector protocol. The physical difference in the Series A and B connectors insures proper end user connectivity. The A connector is the principle means of connecting USB devices directly to a host or to the downstream port of a hub. All USB devices must have the standard Series A connector specified in this chapter. The B connector allows device vendors to provide a standard detachable cable. This facilitates end user cable replacement.
Figure 2-10 illustrates the keyed connector protocol.
Series A Connectors | Series B Connectors | |
◆Series A plugs are | ◆Series B plugs are | |
always oriented upstream | always oriented downstream towards | |
towards the Host System | the USB Device | |
A Plugs | B Plugs | |
(From the | (From the | |
USB Device) | Host System) | |
| B Receptacles | |
A Receptacles | (Upstream Input to the | |
USB Device or Hub) | ||
(Downstream Output | ||
| ||
from the USB Host orHub) |
|
Figure 3-10 Keyed Connector Protocol
The following list explains how the plugs and receptacles can be mated:
•Series “A” receptacle mates with a Series “A” plug. Electrically, Series “A” receptacles function as outputs from host systems and/or hubs.
•Series “A” plug mates with a Series “A” receptacle. The Series “A” plug always is oriented towards the host system.
•Series “B” receptacle mates with a Series “B” plug (male). Electrically, Series “B” receptacles function as inputs to hubs or devices.
•Series “B” plug mates with a Series “B” receptacle. The Series “B” plug is always oriented towards the USB hub or device.
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