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Entry type: FAQ, Entry ID: 17452619, Entry date: 06/03/2014

What are the requirements for using the "Prepare Line Diagnostics" function?

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The in-process line diagnostics of the diagnostic repeater permit you to detect and locate line faults early on.
To be able to localize a problem in the network, the diagnostic repeater must know the topology of the PROFIBUS subnet to which it is connected. Using its "Prepare Line Diagnostics" function, the diagnostics repeater determines the distances to all the nodes.

You trigger the "Prepare Line Diagnostics" function in the STEP 7 Hardware Configuration or in NetPro via the menu "PLC > PROFIBUS > Prepare Line Diagnostics".

Alternatively you can use the system function SFC103 "DP_TOPOL" to trigger topology determination in the user program of the CPU. When you call the system function SFC103 "DP_TOPOL", the diagnostic repeaters on a DP master system are addressed.

You can run topology determination only for one DP master system at a time.

Determining the topology is the requirement for detailed display of the fault location when line errors occur. Run topology determination with the SFC103 "DP_TOPOL" each time you set up or change the physical structure of a DP master system.

Changes to the physical structure include the following:

  • Change of line lengths
  • Addition or removal of nodes or components with repeater function
  • Change of node addresses

The SFC103 "DP_TOPOL" has the following input parameters.

Input parameters Data type Description
REQ BOOLEAN REQ=1: Trigger topology determination
R BOOLEAN R=1: Stop topology determination
DP_ID INT ID of the DP master system whose topology is to be determined
Table 01

The SFC103 "DP_TOPOL" has the following output parameters.

Output parameters Data type Description
RET_VAL INT If a error occurs during processing of the function, the return value includes the relevant error code.
BUSY BOOLEAN BUSY=1: Topology determination has not yet finished.
DPR BYTE PROFIBUS address of the diagnostic repeater reporting the error.
DPRI BYTE Measuring segment of the diagnostic repeater reporting the error:
  • Bit 0 = 1: Temporary faults on Segment DP2
  • Bit 1 = 1: Permanent faults on Segment DP2
  • Bit 4 = 1: Temporary faults on Segment DP3
  • Bit 5 = 1: Permanent faults on Segment DP3
Table 02

Permanent faults
Permanent faults have been detected on the network which prevent successful determination of the topology. You can use SFC13 "DPNRM_DG" or STEP 7 to read out the details about the cause as diagnostics data.

Temporary faults
Temporary faults have been detected on the network which prevent successful determination of the topology. There might be a loose connection or multiple fault. No clear cause can be traced for the faults.

If a diagnostic repeater reports a fault, the SFC103 "DP_TOPOL" writes to the DPR and DPRI outputs for the duration of an SFC run. If multiple diagnostic repeaters of the selected DP master system report faults, the SFC103 "DP_TOPOL" writes the data of the first diagnostic repeater to report a fault to the DPR and DPRI. You can read out the complete diagnostics data with SFC13 "DPNRM_DG" or STEP 7.

Hardware requirements
The following S7-300 CPUs support system function SFC103:

CPUs Article number Note
CPU313C-2 DP 6ES7313-6CF03-0AB0 Firmware V2.6 onwards
CPU313C-2 DP 6ES7313-6CG04-0AB0  
CPU314C-2 DP 6ES7314-6CG03-0AB0 Firmware V2.6 onwards
CPU314C-2 DP 6ES7314-6CH04-0AB0  
CPU314C-2 PN/DP 6ES7314-6EH04-0AB0  
CPU315-2 DP 6ES7315-2AG10-0AB0 Firmware V2.6 onwards
CPU315-2 DP 6ES7315-2AH14-0AB0  
CPU315-2 PN/DP 6ES7315-2EH13-0AB0 Firmware V2.5 onwards
CPU315-2 PN/DP 6ES7315-2EH14-0AB0  
CPU315F-2 DP 6ES7315-6FF01-0AB0 Firmware V2.6 onwards
CPU315F-2 DP 6ES7315-6FF04-0AB0  
CPU315F-2 PN/DP 6ES7315-2FH13-0AB0 Firmware V2.5 onwards
CPU315F-2 PN/DP 6ES7315-2FJ14-0AB0  
CPU315T-2 DP 6ES7315-6TH13-0AB0  
CPU315T-3 PN/DP 6ES7315-7TJ10-0AB0  
CPU317-2 DP 6ES7317-2AJ10-0AB0 Firmware V2.5 onwards
CPU317-2 DP 6ES7317-2AK14-0AB0  
CPU317-2 PN/DP 6ES7317-2EK13-0AB0 Firmware V2.5 onwards
CPU317-2 PN/DP 6ES7317-2EK14-0AB0  
CPU317F-2 DP 6ES7317-6FF03-0AB0 Firmware V2.5 onwards
CPU317F-2 DP 6ES7317-6FF04-0AB0  
CPU317F-2 PN/DP 6ES7317-2FK13-0AB0 Firmware V2.5 onwards
CPU317F-2 PN/DP 6ES7317-2FK14-0AB0  
CPU317T-2 DP 6ES7317-6TK13-0AB0  
CPU317T-3 PN/DP 6ES7317-7TK10-0AB0  
CPU319-3 PN/DP 6ES7318-3EL00-0AB0  
CPU319-3 PN/DP 6ES7318-3EL01-0AB0  
CPU319F-3 PN/DP 6ES7318-3FL00-0AB0  
CPU319F-3 PN/DP 6ES7318-3FL01-0AB0  
Table 03

If you do not want to trigger topology determination via the CPU, but want to fetch the diagnostics data exclusively from the diagnostic repeater, you call system function SFC59 "RD_REC" or system function block SFB52 "RDREC" for reading data records. 

The following S7-400 CPUs support system function SFC103:

CPUs Article number Note
CPU 412-1 6ES7412-1XF03-0AB0 Firmware V3.1 onwards
CPU 412-1 6ES7412-1XF04-0AB0  
CPU 412-1 6ES7412-1XJ05-0AB0  
CPU 412-2 DP 6ES7412-2XG00-0AB0 Firmware V3.1 onwards
CPU 412-2 DP 6ES7412-2XG04-0AB0  
CPU 412-2 DP 6ES7412-2XJ05-0AB0  
CPU 412-2 PN 6ES7412-2EK06-0AB0  
CPU 412-2 PCI 6ES7673-2CC02-0YA0 V3.4
CPU 412-2 PCI 6ES7673-2CC40-0YA0 V4.0
CPU 414-2 DP 6ES7414-2XG03-0AB0 Firmware V3.1 onwards
CPU 414-2 DP 6ES7414-2XG04-0AB0  
CPU 414-2 DP 6ES7414-2XK05-0AB0  
CPU 414-3 DP 6ES7414-3XJ00-0AB0 Firmware V3.1 onwards
CPU 414-3 DP 6ES7414-3XJ04-0AB0  
CPU 414-3 DP 6ES7414-3XM05-0AB0  
CPU 414-3 PN/DP 6ES7414-3EM05-0AB0  
CPU 414-3 PN/DP 6ES7414-3XM06-0AB0  
CPU 414F-3 PN/DP 6ES7414-3FM06-0AB0  
CPU 414-4 H 6ES7414-4HJ00-0AB0  
CPU 416-2 DP 6ES7416-2XK02-0AB0 Firmware V3.1 onwards
CPU 416-2 DP 6ES7416-2XK04-0AB0  
CPU 416-2 DP 6ES7416-2XN05-0AB0  
CPU 416F-2 DP 6ES7416-2FK04-0AB0  
CPU 416F-2 DP 6ES7416-2FN05-0AB0  
CPU 416-2 PCI 6ES7673-6CC22-0YA0 V3.4
CPU 416-2 PCI 6ES7673-6CC40-0YA0 V4.0
CPU 416-3 DP 6ES7416-3XL00-0AB0 Firmware V3.1 onwards
CPU 416-3 DP 6ES7416-3XL04-0AB0  
CPU 416-3 DP 6ES7416-3XR05-0AB0  
CPU 416-3 PN/DP 6ES7416-3ER05-0AB0  
CPU 416-3 PN/DP 6ES7416-3ES06-0AB0  
CPU 416F-3 PN/DP 6ES7416-3FR05-0AB0  
CPU 416F-3 PN/DP 6ES7416-3FS06-0AB0  
CPU 417-4 6ES7417-4XL00-0AB0 Firmware V3.1 onwards
CPU 417-4 6ES7417-4XL04-0AB0  
CPU 417-4 6ES7417-4XT05-0AB0  
CPU 414-4 H 6ES7414-4HJ00-0AB0 V3.1 onwards
CPU 414-4 H 6ES7414-4HJ04-0AB0  
CPU 414-4 H 6ES7414-4HM14-0AB0  
CPU 417-4 H 6ES7417-4HL01-0AB0 V3.1 onwards
CPU 417-4 H 6ES7417-4HL04-0AB0  
CPU 417-4 H 6ES7417-4HT14-0AB0  
CPU 412-3 H 6ES7412-3HJ14-0AB0  
CPU 412-5H PN/DP 6ES7412-5HK06-0AB0  
CPU 414-5H PN/DP 6ES7414-5HM06-0AB0  
CPU 416-5H PN/DP 6ES7416-5HS06-0AB0  
CPU 417-5H PN/DP 6ES7416-5HT06-0AB0  
Table 04

If you do not connect the PROFIBUS for the diagnostics repeater directly to the CPU interface, but via a PROFIBUS CP, then the "Prepare Line Diagnostics" function must be supported by the CPU and by the CP.

The following S7-400 CPs support the "Prepare Line Diagnostics" function:

CP Article number Note
CP 433-5 Extended 6GK7443-5DX04-0XE0 Firmware V6.1 onwards
CP 433-5 Extended 6GK7443-5DX04-0XE1  
CP 433-5 Extended 6GK7443-5DX05-0XE0  
Table 05

If you do not want to trigger topology determination via the CPU, but want to fetch the diagnostics data exclusively from the diagnostic repeater, you call system function SFC59 "RD_REC" or system function block SFB52 "RDREC" for reading data records. 

Further Information
More information about line diagnostics with the diagnostic repeater and a sample program are available in the manual entitled "SIMATIC Diagnostic Repeater for PROFIBUS-DP" in Entry ID 7915183.

PG/PC system requirements

Setting under "Set PG/PC interface..."
For the "Prepare Line Diagnostics" function, you select the access point "S7ONLINE (STEP 7) > CP5xxx.PROFIBUS" under "Set PG/PC interface...".

Implementable communication processors
The following PROFIBUS PC CPs support the "Prepare Line Diagnostics" function on the PROFIBUS DP:

  • CP5511
  • CP5512
  • CP5611 (A2)
  • CP5612
  • CP5621
  • CP5622
  • CP5711

Software requirements
You need STEP 7 V5.2 SP1 or higher to trigger the "Prepare Line Diagnostics" function that supports the diagnostic repeater as from article no. 6ES7972-0AB01-0XA0.

Security information
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