Resolving Red Fault Not Displayed in PCS 7 CEMAT Group Icon

Problem Overview

In SIMATIC PCS 7 V7.1 SP3 with the CEMAT mineral processing library, an equipment-level fault (e.g. on a drive, valve or annunciator block) is signalled in the operator's group faceplate by a flashing red letter F in the group block icon. When the equipment is grouped, its fault is supposed to be summarised and propagated upward so that the area/group display also shows the red fault indicator. In the field, the drive faceplate and the per-equipment block icon update correctly, but the red F never appears in the group block icon. Group-level annunciator windows and the maintenance overview do not show the fault either, which defeats the purpose of grouping for a cement plant operator.

The behaviour is not caused by the OS server runtime being down, nor by a WinCC redundancy issue - it is a CFC interconnection / block-icon configuration issue on the AS side. This article documents the exact signal chain between a drive block and the group block, the connectors that must be wired, the parameters that suppress aggregation, and the order in which to verify the chain end-to-end.

Architecture of Group Fault Aggregation in CEMAT

CEMAT (the cement and minerals library for PCS 7) builds the operator view from three logical layers:

1. Equipment layer - the lowest-level blocks: MOT (motor / drive), VAL (valve), ANN (annunciator), MEAS (measurement), DOSE (proportioning), etc. Each of these blocks exposes a static fault (latched) and a dynamic fault (current) condition.
2. Group layer - the GRP block (also referenced as the group block / Gruppensymbol). It receives the summary fault from all assigned equipment blocks via its GR_LINK1 / GR_LINK2 inputs.
3. Area layer - the AREA block collects the summarised fault from one or more GRP blocks for plant-wide overviews.

The red F in the group block icon comes from the group block's GFLT (group fault) status. That status is the OR of the GR_LINK1 and GR_LINK2 inputs, both of which are themselves ORs of the equipment faults routed through the equipment block's group-output connector GR_LINK (or GSTZ, depending on block type and CEMAT version).

If any of the wires in this chain is missing, mis-routed, or held off by a parameter (most commonly EMZS = 1), the group block never sees a true on its fault input, the icon stays grey, and the red F is not displayed.

Key Connectors and Parameters

The connectors below are the ones most frequently involved in a "no red F on group icon" symptom. Connector names follow the CEMAT / PCS 7 CFC library naming; case-sensitive in the symbol I/O.

Root Cause Analysis Matrix

Prerequisites

• PCS 7 engineering station with the project open in SIMATIC Manager (or V8+ with the same project in TIA Portal / PCS 7 engineering tool) and the matching CEMAT library installed.
• Read access to the relevant S7 program and CFC charts. The group block and the equipment block(s) are normally in the same chart or in charts of the same unit.
• An OS server / WinCC Explorer in runtime, or a simulation runtime, so the block icon can be observed live.
• A reproducible fault: a drive wired through a digital input, a forced tag, or a real field signal - so you can confirm that the red F is supposed to appear and then observe the fix.
• For verification, the ability to open the equipment faceplate and the group faceplate side-by-side.

Step-by-Step Verification Procedure

Work from the equipment side upward. Do not change any wiring until each step has been checked.

Step 1 - Confirm the equipment actually carries a fault

1. Open the operator faceplate of the drive / equipment that is suspected.
2. Trigger a real fault (e.g. remove the run permit, or force FLT / SFLT high for one cycle).
3. Verify that the per-equipment block icon now shows the red flashing F.
4. If the equipment icon itself does not show the F, the problem is on the equipment block, not on the group. Investigate the FLT/SFLT input, the permit chain and the block's OP_MODE before continuing.

Step 2 - Read the EMZS / GrFltLck input

1. In CFC, double-click the equipment block to open its I/O view.
2. Locate the EMZS input. Right-click and select "Go to interconnection" or read the value directly with the CFC online view.
3. Confirm EMZS = 0. The PCS 7 / CEMAT documentation defines the default state as 0; if a previous engineer has set it to 1, the block is intentionally excluded from group summarising.
4. If EMZS is wired from another tag, follow that tag back to its source - it is often a maintenance switch driven by an operator input.

Step 3 - Verify the GR_LINK wire to the group

1. Open the equipment block's output GR_LINK. Right-click and select "Go to interconnection".
2. The target must be GR_LINK1 or GR_LINK2 of the GRP block. Any other target (e.g. an OR block, a status-only input, an unused BOOL) breaks the path.
3. If the wire does not exist, draw it: click the GR_LINK pin of the equipment, drag to the GR_LINK1 pin of the group. Use GR_LINK1 for the first equipment, GR_LINK2 for additional equipment that has its own aggregation.
4. For older CEMAT versions the path goes through SST / EST of the drive into GSTZ of the group. Both styles are valid - what matters is that the equipment output that carries the fault is actually connected.

Step 4 - Check the run sequence of the group block

1. Right-click the GRP block - Object properties - "Run sequence" tab.
2. Confirm the run sequence matches the task class of the equipment block. The safest pattern is to put all blocks in the same run sequence within the same task (typically OB1 for the slow path, or a dedicated OB35 cycle for fast groups).
3. Mismatched run sequence is one of the most common intermittent causes: the equipment updates faster than the group, and the group faceplate shows a stale value.

Step 5 - Check the EMFR input on the drive

1. EMFR must be 1 if you want the operator to be able to acknowledge / reset the fault at the group faceplate.
2. If EMFR = 0 the group faceplate reset button is greyed out; the red F will persist until the drive is reset from the equipment faceplate. This does not by itself prevent the F from appearing, but it is a frequent adjacent complaint.

Step 6 - Verify the OS picture and block icon

1. Open WinCC Explorer on the OS server and locate the picture that is supposed to contain the group icon.
2. Right-click the block icon - "Configuration" - check that the instance name matches the GRP block exactly (case-sensitive, e.g. GRP_MILL1).
3. If the block icon points to a different instance, the runtime tag is correct but the picture is not displaying it.
4. Recompile the OS, transfer to the server, and restart the runtime if the picture was modified offline.

Step 7 - Live monitoring with CFC online view

1. Open CFC online on the chart that contains the group block.
2. Force a fault on the drive by toggling SFLT or the field input that the drive uses.
3. Watch in real time:
   • Drive's SFLT = 1
   • Drive's GR_LINK = 1
   • Group's GR_LINK1 = 1 (or GR_LINK2 = 1)
   • Group's GFLT = 1
4. If any of these transitions is missing, the break point is exactly where the chain stops.

CFC Configuration Example

Minimal wiring for a single-drive group. The drive block is MOT_1, the group block is GRP_LINE1.

// Drive block (MOT_1) - output to the group
MOT_1.GR_LINK  ->  GRP_LINE1.GR_LINK1

// Drive block maintenance lock - keep at 0 to include in group
MOT_1.EMZS     = 0

// Group block - output to the area
GRP_LINE1.GSTZ ->  AREA_PLANT.G_LINK1

// Group run sequence
GRP_LINE1      : OB1 / run sequence 5 (or matching task class)
MOT_1           : OB1 / run sequence 4

For multi-drive groups, additional drives connect to GRP_LINE1.GR_LINK2 (and, in larger groups, to the next group's GR_LINK1 in a daisy chain). The group ORs both channels internally, so the red F appears as soon as any of the contributing drives asserts its GR_LINK.

Block Icon / WinCC OS Configuration

The block icon on the group picture is generated by the WinCC OS compilation from the CFC chart. The most common OS-side issues are:

• Wrong block type selected for the icon. The block icon wizard is configured for MOT, but the picture element represents a GRP. The icon's status bits are read from the wrong tag namespace.
• Picture compiled with an old S7 program. The group block was renamed, the picture was not re-compiled, and the tag prefix no longer exists.
• Authorisation level hides the red F. The user logged into WinCC does not have the authorisation to see maintenance faults; the red F is hidden, but the underlying tag is still 1. Verify with a user that has the full maintenance authorisation.

Remediation: open the picture in Graphics Designer, double-click the block icon, confirm the instance name, re-run OS compilation from the S7 program, and download the new picture to the OS server.

Verification

1. With the project compiled and downloaded, log into the OS runtime as a maintenance user.
2. Force a fault on the drive (simulated or real).
3. Confirm on the equipment faceplate: red flashing F.
4. Confirm on the group block icon: red flashing F, propagated from the drive.
5. Confirm on the area button: red F aggregated from the group.
6. Acknowledge the fault from the group faceplate. With EMFR = 1, the red F transitions to a steady icon and then clears once the underlying fault is removed.
7. Reset the forced fault and confirm all three layers (drive, group, area) clear in order.

Common Pitfalls and Edge Cases

• EMZS left at 1 from a maintenance session. The operator set EMZS = 1 to suppress a known nuisance fault during a planned maintenance window, and the value was never returned to 0. Always check this input first.
• GR_LINK and GSTZ confusion across CEMAT versions. V7.x CEMAT used SST/EST/GSTZ for grouping; V8.x and V9.x often use GR_LINK/GFLT. A mixed library (e.g. newer GRP with older MOT) silently breaks the chain. Compare the family of the blocks in Library - Open with the version deployed in the project.
• Compile order. If the GRP block is compiled before the equipment blocks, the group can briefly show fault on a clean plant until the next download. Always run a full Compile - All (Charts + SFC + OS) after restructuring the group.
• Simulated vs real field signal. A simulated FLT from a CFC chart may not pass through a SIMOCODE / soft starter's actual Fault relay. The drive's FLT input is 0, the drive never asserts GR_LINK, and the group never sees a fault. Force at the drive's FLT pin, not at the field wiring.
• Redundant AS / OS configuration. On a redundant OS pair, the group picture on the standby server may show a stale icon until the next role switch. Refresh the picture manually or trigger a controlled failover to confirm the icon is current on the new master.

Reference Parameters - CEMAT GRP / MOT Block (V7.1 SP3)

FAQ