
FLC Interface
PROFIBUS Controller SPC 4®-2 LF
C79000-G8976-C157-3
37
5.1.2 Control
Byte
Bit Position
Meaning
7 6
5
4
3 2
1
0
SAP
locked
SDN/ DDB
filter
RS/RA or
UE
RR
IN USE
Buffer available
Control byte
Buffer available
Bits 0-
2
These three bits are used as a counter for resources provided externally. The FLC increments the 3 bits
as soon as a resource is available. The SPC 4-2 decrements the 3 bits when a received block was
indicated. When it receives, the SPC 4-2 reads the 3 bits after it has received the complete frame. If the
counter reading is zero, it aborts reception, sets the event flap 'No Resource' (RR, see below) and
replies with no resource (SD1 response)
Exception:
If DP mode = 1 is set, buffer available is
not
changed by the SPC 4-2 in DEFAULT SAP. Buffer
available must, however, be set to higher than zero otherwise the response will be no resource.
Bit 3
IN USE
The SPC 4-2 sets this bit as soon as it has entered the complete frame of a request frame in the
indication buffer. It resets it when an indication has been executed (valid or invalid). If the FLC wants to
assign a new reply block, it must wait until the bit is reset. Only then can it reload the reply update
pointer (under Mem-Lock). This prevents the FLC from reloading SPC 4-2 data when sending.
Exception:
If DP mode = 1 is set, the in-use bit is
not
set by the SPC 4-2 in the DEFAULT SAP. A correctly
received request frame at the DEFAULT SAP is
not
entered in the indication queue and
not
indicated.
Bit 4
RS/RA or UE
No service activated/ Service access point blocked or user error:
the SPC 4-2 sets this flag when
the validation of the request SA was negative (request SA does not match received SA; in other words
the call comes from an unauthorized node). The SPC 4-2 replies with
Service Access Point Blocked
[RA]
in the PA mode
or no service activated [RS]
in the PROFIBUS mode (SD1 response). This flag
is also set when request SA = 7FH; in other words, the SAP is inactive. The SPC 4-2 replies with
No
service activated
[RS]
(SD1 response). This bit is set as a user error [UE] is the SAP was locked. The
SPC 4-2 replies with
User Error [UE]
(SD1 response).
Bit 5
RR = No Resource
The SPC 4-2 sets this bit if the content of the buffer available bits is zero after receiving the frame
header; in other words, the FLC has not provided any resources or the queue is full. In both cases, the
SPC 4-2 replies with
No Resource[RR]
(SD1 response).
Bit 6
SDN-/DDB Filter
This bit allows the SDN-/DDB filter to be activated
0 =
The "Reply-Update-Ptr/SDN-/DDB-Tln-Tab-Ptr" pointer points to the Reply-on-Indication-Block
and therefore to the response to be sent. If the pointer = 00H, there is no response buffer and
the SPC 4-2 replies with an SRD request with a short confirmation (SC).
1 =
The "Reply-Update-Ptr/SDN-/DDB-Tln-Tab-Ptr" pointer points to the node table and the SPC 4-
2 is "Subscriber" for this SAP. The SDN-/DDB-Tln list is evaluated during a "Subscriber for
DDB-Response" access or SDN request.
Bit 7
SAP locked
The SAP is not currently accepting data. If the SPC 4-2 receives data for this SAP, it sets the event flag
user error (UE) and replies with user error (SD1 response).
Table 5-2 Control Byte
Summary of Contents for SIMATIC NET SPC 4-2 LF
Page 9: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 9 Introduction 1 ...
Page 11: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 11 Functional Overview 2 ...
Page 14: ...PROFIBUS Controller SPC 4 2 LF 14 C79000 G8976 C157 3 ...
Page 15: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 15 Pin Assignment 3 ...
Page 18: ...PROFIBUS Controller SPC 4 2 LF 18 C79000 G8976 C157 3 ...
Page 19: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 19 Memory Assignment 4 ...
Page 32: ...PROFIBUS Controller SPC 4 2 LF 32 C79000 G8976 C157 3 ...
Page 33: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 33 FLC Interface 5 ...
Page 50: ...PROFIBUS Controller SPC 4 2 LF 50 C79000 G8976 C157 3 ...
Page 51: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 51 DP Interface 6 ...
Page 63: ...ASIC Interface PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 63 ASIC Interface 7 ...
Page 107: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 107 Asynchronous Interface 8 ...
Page 114: ...PROFIBUS Controller SPC 4 2 LF 114 C79000 G8976 C157 3 ...
Page 115: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 115 Synchronous Interface 9 ...
Page 125: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 125 Clock Pulses 10 ...
Page 128: ...PROFIBUS Controller SPC 4 2 LF 128 C79000 G8976 C157 3 ...
Page 129: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 129 Processor Interface 11 ...
Page 152: ...PROFIBUS Controller SPC 4 2 LF 152 C79000 G8976 C157 3 ...
Page 153: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 153 Technical Specifications 12 ...
Page 159: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 159 Package 13 ...
Page 165: ...Package PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 165 Figure 13 4 Tray Spezification ...
Page 166: ...PROFIBUS Controller SPC 4 2 LF 166 C79000 G8976 C157 3 ...
Page 168: ...PROFIBUS Controller SPC 4 2 LF 168 C79000 G8976 C157 3 ...
Page 169: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 169 Addresses 15 ...
Page 172: ...PROFIBUS Controller SPC 4 2 LF 172 C79000 G8976 C157 3 ...
Page 173: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 173 Appendix 16 ...
Page 178: ...PROFIBUS Controller SPC 4 2 LF 178 C79000 G8976 C157 3 ...