S7-300 vs S7-400 CiR Compatibility for SIMATIC PDM Online

Overview: PDM, CiR, and the S7-300/S7-400 Boundary

SIMATIC Process Device Manager (PDM) is the Siemens engineering tool for parameterizing field devices on PROFIBUS-PA, HART over PROFIBUS, and HART over WirelessHART networks. Configuration in Run (CiR) is a STEP 7 mechanism that allows the hardware configuration of a running S7 station to be modified without stopping the CPU. The two functions are frequently confused because both touch the same DP/PA master system, but they are independent.

CiR is not required to use PDM online. PDM can always read live parameters, run diagnostics, and write parameter sets to a device that is already present in the configured PROFIBUS-PA topology. CiR is only required when you want to add, remove, or re-address PA slaves on a master system while the CPU is in RUN.

This reference clarifies:

• Which Siemens CPUs support CiR and which do not.
• How to use PDM online against an S7-300 (CPU 6ES7 317-2FK13-0AB0 example) across a PROFINET to PROFIBUS-PA gateway.
• The hardware prerequisites for CiR on ET 200M stations (IM 153-2, active bus elements).
• The STEP 7 V5.5 procedure to enable CiR compatibility on an S7-400 master system.
• How to verify PDM routing and resolve the most common "cannot go online" faults on S7-300.

CiR Functionality and Scope

CiR (Configuration in Run) is documented in the Siemens manual SIMATIC STEP 7 V5.5 - Modifying the System during Operation via CiR. It permits the following modifications on a running PROFIBUS-DP or PROFIBUS-PA master system without CPU stop:

• Add a DP or PA slave that is not yet present in the HW Config.
• Remove a DP or PA slave.
• Change the PROFIBUS address of a DP or PA slave.
• Replace a faulty DP slave with a new one of the same type at the same slot.
• Modify the maximum number of slaves reserved in a master system.

CiR works by reserving empty slots (CiR elements) in the master system. STEP 7 inserts a fixed number of reserved addresses and slots at configuration time, and these reserved entries are filled when an actual slave is wired in at runtime. The cost of CiR is therefore a permanent slice of PROFIBUS bandwidth and address space consumed by the reservations, regardless of whether you ever add a device.

CPU Compatibility Matrix for CiR

The CPU in the original query, 6ES7 317-2FK13-0AB0, is the CPU 317F-2 PN/DP - an S7-300 fail-safe CPU with:

• 1 PROFINET interface (X1, 2-port switch, 100 Mbit/s).
• 1 PROFIBUS-DP master/slave interface (X2, up to 12 Mbit/s).
• 1.5 MB work memory code, 2 MB data (typical for this MLFB).
• Integrated fail-safe functionality.

This CPU cannot host CiR modifications. It can, however, act as an S7 router so that PDM can reach devices on a downstream PROFIBUS-PA segment.

What PDM Can Do Without CiR

PDM can be used online on any S7-300 or S7-400 master system that has the PA slaves in its configured HW Config. The following operations do not require CiR:

• Read live process values (pressure, temperature, flow, level, valve position) from PA slaves.
• Read and write device parameters (range, units, damping, alarm limits, scaling).
• Run device diagnostics (status, simulation, event log, trend, lifecycle data).
• Generate the PROFIBUS-PA topology as a PDF or XML report for documentation.
• Store the final parameter set as a lifecycle record on the engineering station.
• Update device firmware where the device vendor supports it via PDM (e.g., SITRANS P, SITRANS F, SIPART PS2, SITRANS LR560, MAG 6000).

What PDM cannot do without CiR on an S7-300 is bring a brand-new PA slave into a live master system that does not yet contain the slave in HW Config. The CPU must go STOP, the slave must be added in HW Config and downloaded, and only then can PDM reach it. This is the limitation that CiR is designed to remove, and it is the reason the CiR function is associated with PDM at all.

PROFINET to PROFIBUS-PA Gateway Architecture

An S7-300 PROFINET CPU cannot talk directly to a PROFIBUS-PA device. A two-stage gateway is required. The standard topology is:

1. Engineering station with PDM on the plant Ethernet (PROFINET segment).
2. PROFINET line or ring through the X1 port of the CPU 317F-2 PN/DP.
3. IE/PB Link PN IO (typical MLFB 6GK1411-5AB00) bridges PROFINET to PROFIBUS-DP. It is a PROFINET IO device on the CPU side and a PROFIBUS-DP master on the downstream side.
4. DP/PA Coupler (FDC 157-0 AC82, MLFB 6ES7157-0AC82-0XA0) for simple segments - transparent physical connection, max 31 PA devices, no address translation. The coupler is invisible to PDM and consumes no PROFIBUS address.
5. DP/PA Link (FDC 157, MLFB 6ES7157-0AA82-0XA0 family) for larger segments - acts as a PROFIBUS-DP slave and exposes each PA device as a separate DP slot to the upstream master. The Link itself occupies one DP address.
6. PROFIBUS-PA trunk and spurs to field devices.

For an S7-300 with both PROFINET and PROFIBUS-DP, the X2 PROFIBUS-DP port is also a valid exit point. If the PA devices are local to the S7-300 station, the IE/PB Link PN IO can be omitted and the DP/PA Coupler or DP/PA Link connects directly to X2.

Address Translation Between DP and PA

PROFIBUS-PA devices use one-byte addresses (0 to 126 physically, with 0 reserved for the master). The DP/PA Link translates the PA address into a DP slot. The translation table is configured in HW Config under the DP/PA Link properties, in the PA Field Devices tab. Each PA device must be entered with:

• Vendor-specific Device ID (taken from the device GSD or EDD catalog).
• PROFIBUS-PA address (must be unique on the segment).
• Slot assignment on the DP side (slot 0 is typically reserved for the DP/PA Link itself; PA devices occupy slot 1 onward).

PDM uses the slot-assigned DP view to talk to each PA device. If the DP/PA Link is misconfigured, PDM shows "device not found" even when the physical wiring is correct.

Configuring PDM Routing on S7-300 (CPU 317F-2 PN/DP)

The S7-300 must be configured as an S7 router so PDM can walk the path PC → Ethernet → CPU PN port → CPU DP port → IE/PB Link → DP/PA Link → PA device. The procedure in STEP 7 V5.5 is:

1. Open the S7 station in HW Config.
2. Select the CPU 317F-2 PN/DP. Open Object Properties > Interface > Parameter for the PROFINET interface and tick Use this CPU as a router (S7-Routing). Repeat for the PROFIBUS-DP interface.
3. Insert the IE/PB Link PN IO under the CPU's PROFINET interface. Use the matching GSD file (GSDML-Vx.x-Siemens-IE/PB-Link_PNIO-... from the Siemens GSD catalog).
4. Insert the DP/PA Link or DP/PA Coupler downstream of the IE/PB Link on the PROFIBUS subnet. Assign a unique PROFIBUS address to the DP/PA Link (default 33 for the first link).
5. Open the DP/PA Link properties, switch to the PA Field Devices tab, and add each PA device with vendor ID, PA address, and slot.
6. Save, compile, and download HW Config to the CPU 317F-2 PN/DP. The CPU must be in STOP for the first download.
7. Configure the engineering station's PG/PC interface in the SIMATIC Manager to the correct Ethernet adapter (TCP/IP → ISO on TCP routing).
8. In PDM, open Device → Communication → Assign Device Address and enter the full S7 route, e.g. CPU 317F-2 PN/DP.PN : IE/PB Link PN IO.DP : DP/PA Link Slot 5.

CiR Hardware Prerequisites (ET 200M and Active Backplane)

CiR is not only a CPU feature - it imposes hardware constraints on the ET 200M stations attached to the CiR-enabled master system. The Siemens manual lists the following requirements:

• The ET 200M must use an IM 153-2 (active backplane capable) at MLFB 6ES7153-2BA00-0XB0 or higher, or an IM 153-2FO (fiber-optic) at MLFB 6ES7153-2BB00-0XB0 or higher.
• The ET 200M must be installed with active bus elements (the BM 153 / BM 153-2 backplane modules that pass through the backplane bus to the next module). Modules can be pulled or inserted in RUN only with active bus elements in place.
• There must be sufficient free slot space for the planned expansion (modules cannot be added at the end of a packed ET 200M; an empty slot must be reserved).
• The ET 200M may not be implemented as a DPV0 slave via a generic GSD file. It must be configured as a DPV1 slave with the Siemens-specific GSD, or via the type file from the Siemens catalog. DPV0 slaves cannot be added or removed in RUN because the cyclic data layout is fixed at startup.

Enabling CiR in STEP 7 V5.5

CiR is enabled per master system, not per CPU. Procedure for an S7-400 station:

1. Open the S7-400 station in HW Config.
2. Select the DP master system line (not a slave, the master itself).
3. Open the Edit > Master system > Enable CiR compatibility menu. The corresponding PDF manual SIMATIC Modifying the System during Operation via CiR (S7Cir_e.pdf) describes this step on the DP master system menu.
4. STEP 7 inserts CiR elements - empty slots and reserved PROFIBUS addresses - into the master system. The reserved count is configurable; the typical value is 2 to 8 depending on the expected growth.
5. Save and download HW Config to the CPU 412/414/416/417.
6. Verify with PLC > Module Information > Diagnostic Buffer that no CiR-related startup errors are present.

CiR objects occupy diagnostic resources on the CPU. If the CPU's diagnostic buffer is full at the moment of an insertion event, the CiR operation may be rejected. The S7-400 diagnostic buffer is large (up to 3200 entries depending on CPU), so this is rarely an issue, but on a CPU 412 with a heavy event log, raise the buffer retention or clear older entries before attempting a CiR modification.

PDMEN, PDM, and the SIMATIC PCS 7 Context

PDM is part of the SIMATIC PCS 7 distributed control system and shares its communication stack with STEP 7. The communication architecture is documented on the Siemens product page SIMATIC Process Device Manager (PDM). For PCS 7 V8.2 and later, PDM is integrated into the PCS 7 engineering toolset. For PCS 7 V9.0 and later, PDM also supports PROFINET field devices directly, removing the IE/PB Link and DP/PA Link from the path on greenfield installations.

PDM versions are tied to STEP 7 / TIA Portal versions:

PDM V8.x is the last line that can be added to a STEP 7 V5.5 project that also contains a CPU 317F-2 PN/DP. TIA Portal routes to the same S7-300 from PDM V9.x without issue, but the project format is different.

Diagnostic and Verification Procedures

Follow this checklist when PDM cannot go online against a PA device on an S7-300 (e.g., CPU 317F-2 FK13-0AB0):

1. Open Start > SIMATIC > STEP 7 > Set PG/PC Interface. Confirm the engineering station uses the same Ethernet adapter that has the S7-300 PROFINET subnet configured.
2. In SIMATIC Manager, PLC > Accessible Nodes over Ethernet. The CPU 317F-2 PN/DP must appear. If it does not, the PC cannot reach the PROFINET port and routing is impossible.
3. Open the online diagnostic of the CPU. Verify firmware version and that the PROFINET interface is in RUN with no partner errors.
4. In the IE/PB Link PN IO Web diagnostics (open browser to the link's PROFINET name resolved as URL or via the integrated Web server), check the downstream PROFIBUS-DP segment. Slave-by-slave status, diagnostic buffer, and signal quality should be reported.
5. On the DP/PA Link, use the Link's Web diagnostics or the HW Config DP/PA Link > PA Field Devices view to verify that each PA device shows online status and a valid PROFIBUS-PA address.
6. In PDM, right-click the device in the plant view and select Go Online. If the route is wrong, PDM reports the failing hop. Correct the route and retry.
7. For persistent "no connection" faults, capture the diagnostic buffer of the S7-300 (PLC > Module Information > Diagnostic Buffer) and the diagnostic buffer of the IE/PB Link. The S7-300 reports a routing entry error (event ID 0x03A2) when it is asked to forward a request to a downstream subnet that has no slave at the specified address.

Troubleshooting Matrix

Field-Proven Notes and Caveats

• PDM's "commissioning" route and the SIMATIC Manager "online" route use the same S7 routing tables but separate cache files. Clear the PDM communication cache (%LOCALAPPDATA%\Siemens\Automation\PDM\Cache) after any major STEP 7 recompile.
• The IE/PB Link PN IO defaults to PROFIBUS-DP master with address 1. If a real PROFIBUS master (CPU X2) is on the same segment, change the Link's address to a non-conflicting value before powering the bus.
• On an S7-300 PN/DP CPU used as a router, the PROFINET interface must be configured with the S7 subnet ID. The subnet ID is auto-generated on first compile and is the binding that PDM uses for route resolution.
• PDM HART over PROFIBUS devices (e.g., HART concentrators) use the same routing and CiR rules as PA devices. The HART device catalog inside PDM is the HART Communication Foundation Catalog, updated separately from the EDD libraries.
• If you must add a brand-new PA slave to an S7-300 PROFINET CPU in RUN, the supported workaround is to add the device to HW Config offline, recompile, and use the CPU's file system or a controlled S7-400 master to insert the change. On a pure S7-300 station, a CPU stop is unavoidable.
• The CIr feature has a documented performance cost: every CiR element consumes one PROFIBUS address and one diagnostic slot. For a master system with 32 slaves, reserving 4 CiR addresses limits the master to 28 active slaves, not 32.

Related Documents and Standards

For deeper reading, consult the official Siemens documentation set used in this article:

• SIMATIC STEP 7 V5.5 - Modifying the System during Operation via CiR (entry ID 45531308)
• SIMATIC Modifying the System during Operation via CiR (S7Cir_e.pdf)
• SIMATIC Process Device Manager (PDM) product page

Refer to the IEC 61158 / IEC 61784 standards for PROFIBUS-PA behavior, and the PROFIBUS Nutzerorganisation (PNO) profile documents for PA device integration. These are normative references; verify against the latest revision before specifying a CiR-enabled architecture.