Siemens SIMOTRAS 6SG7050, Operating Instructions Manual

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Function descriptions 01.04
9-22
SIEMENS AG 6SG7000-0BA76
SIMOTRAS HD Operating Instructions
9.9.1 Serial interfaces with USS
®
protocol
Specification for the USS
®
protocol: Order No. E20125-D0001-S302-A1
The SIEMENS USS
®
protocol is implemented in all digital converter devices supplied by SIEMENS. It
can be used to provide a point-to-point or bus-type link to a master station. Any mixture of converter
types can be connected up to the same bus line. The USS protocol makes it possible to access all
relevant process data, diagnostic information and parameters of the SIMOTRAS converter.
The USS protocol is a pure master-slave protocol. In this case, a converter device can only ever
function as slave. Converter devices will transmit a telegram to the master only if they have received
one from it first. In other words, converters linked via the USS protocol cannot exchange data directly
with one another (they can do this only via a peer-to-peer link).
Useful data which can be transferred via the USS protocol
Sheets G170 to G172 in Section 8 show how useful data can be interconnected and list the
parameters relevant for configuring USS interfaces.
If parameters need to be read and/or written via the USS interface, then "Parameter data length"
(P782, P792, P802) must be set to 3, 4 or 127 (select setting 4 only if double word parameters need to
be transferred). If parameters do not need to be transferred, the "Parameter data length" must be set
to 0.
The number of process data words to be transferred is basically identical for the transmit and receive
directions and can be set in "Process data length" (P781, P791, P801). Numeric representation "100%
equals 4000h = 16384d" applies to all connectors.
Transfer of double-word connectors:
In the receive direction, the values of any two adjacent connectors (K) are combined to form a double-
word connector (KK) (e.g. K2002 and K2003 to KK2032). These double-word connectors can be
connected in the usual way to other function blocks. For details of how to connect with double-word
connectors, see Section 9.1, subsection "The following rules apply to the selection of double-word
connectors".
In the transmission direction, a double-word connector is applied by entering the same double-word
connector at two contiguous indices of the selection parameter.
Examples:
.04
.01
.03
.02
P784
32
401
K0032
KK9498
KK9498
K0401
Word
L-Word
Word
H-Word
9498
9498
K
K
K
K
.04
.01
.03
.02
P784
Word
H-Word
Word
H-Word
2 different
double-word connectors
K0032
KK9498
KK9499
K0401
32
401
9498
9499
K
K
K
K
Numeric representation of parameter numbers and values on serial interfaces
The mode of numeric representation of a parameter value is determined by the parameter "type"
assigned to each parameter in the Parameter List. The different types of parameter are explained at
the beginning of the list. Parameters are always transmitted in the form specified in the "Value range"
column of the Parameter List; any decimal point, however, is omitted (example: display value
123.45
→ the number 12345d = 3039h is transferred via the serial interface).
Diagnostics and monitoring functions for USS interfaces
All transmitted and received useful data words can be checked (directly at the internal software
transfer point from/to USS driver) by means of display parameters r810 / r811, r812 / r813 or r814 /
r815.