Siemens Simovert Masterdrives Compendium page 289

Communication / USS
8.1.1 Protocol specification and bus structure
Features
8.1.1.1 Protocol specification
Introduction
8.1-2
The USS protocol has the following significant features:
♦ Supports a multi-point-capable link, e.g. EIA RS 485 hardware or a
point-to-point link, e.g. EIA RS 232.
♦ Master-slave access technique
♦ Single-master system
♦ Maximum 32 nodes (max. 31 slaves)
♦ Operation with variable or fixed telegram length
♦ Simple, reliable telegram frames
♦ The same bus mode of operation as with the PROFIBUS
(DIN 19245 Part 1)
♦ Data interface to the basic unit according to PROFILE variable-
speed drives. This means that, when the USS is being used,
information is transferred to the drive in the same way as with the
PROFIBUS-DP.
♦ Can be used for start-up, service and automation
♦ PC-based service tools (e.g. DriveMonitor) for SIMOREG and
SIMOVERT
♦ Can be easily implemented in customized systems
The USS protocol defines an access technique according to the
master-slave principle for communications via a serial bus. The point-
to-point link is included as a sub-quantity.
One master and a maximum of 31 slaves can be connected to the bus.
The individual slaves are selected by the master using an address
character in the telegram. A slave can never transmit without first being
initiated by the master so that direct information transfer between
individual slaves is not possible. Communication takes place in the half-
duplex mode.
The master function cannot be transferred (single-master system).
The following illustration shows a bus configuration using drive
technology as an example.
6SE7087-6QX70 (Version AD)
Compendium Motion Control
02.2004
Siemens AG
SIMOVERT MASTERDRIVES