S7-315-2 PN/DP PROFINET Communication: PUT/GET Configuration Guide

The SIMATIC S7-315-2 PN/DP (order number 6ES7 315-2EH14-0AB0, firmware V3.3 and successor variants such as 6ES7 315-2FJ14-0AB0) integrates a PROFINET interface that supports both PROFINET IO controller/device operation and standard S7 communication. For peer-to-peer data exchange between two S7-315-2 PN/DP controllers without PROFINET IO, the recommended approach is the PUT/GET instruction pair inside one CPU (the "master"), with the partner CPU acting as the passive S7 server.

This guide covers a typical scenario: one master CPU sending 70 INT values (140 bytes) to a slave CPU and reading back 40 INT values (80 bytes) from that same slave. Both controllers are physically connected through their integrated PROFINET ports on a switched Ethernet segment. Implementation uses STEP 7 V5.x or TIA Portal V15.1 and later.

1. Prerequisites

Verify the partner CPU allows PUT/GET access. In STEP 7 V5.x: Properties → Protection. In TIA Portal: Device configuration → Properties → Connection mechanisms → Permit access with PUT/GET communication. The CPU protection level must be set to "No protection" or the password must be entered.

2. Network Planning and IP Addressing

Assign static IP addresses from a dedicated industrial subnet. Avoid DHCP on PROFINET segments.

The PROFINET device name is required only when PROFINET IO devices are connected. For pure S7 communication via PUT/GET, the IP address is sufficient. The default gateway and DNS are not required for a closed industrial segment.

3. Project Structure in STEP 7 V5.6

1. Open SIMATIC Manager and create a new project, e.g., S7_PN_MasterSlave.prj.
2. Insert SIMATIC 300 Station twice: rename to PLC_Master and PLC_Slave.
3. For each station, open Hardware and insert:
   • Rack 0, Slot 1: PS 307 5A (6ES7 307-1EA01-0AA0) — required for configuration only.
   • Rack 0, Slot 2: CPU 315-2 PN/DP, order number 6ES7 315-2EH14-0AB0.
   • Double-click the PN interface (X2) and configure IP address + subnet as in the table above.
4. Save and compile the hardware (Station → Save and Compile).

4. Configuring the S7 Connection

The PUT/GET blocks require a configured S7 connection. Open NetPro on the master station.

1. In NetPro, select the master CPU row.
2. Right-click → Insert New Connection.
3. Connection partner: PLC_Slave. Type: S7 connection.
4. In the connection properties, leave the local ID default (e.g., 1) — this becomes the ID input parameter of PUT/GET.
5. The partner IP address is filled in automatically from the slave's PN interface configuration.
6. Save and compile (NetPro → Network → Save and Compile).

When NetPro compiles, the connection is downloaded to the master on next online operation. The slave does not need a configured connection; it automatically accepts incoming S7 PUT/GET requests when access is permitted.

5. Data Block Layout

Create a shared data block on each CPU. Standard accessible blocks (DBs with Not optimized attribute) must be used; optimized symbolic blocks are reachable but require non-standard handling in some TIA versions.

5.1 Master DB (DB100, master CPU)

DATA_BLOCK "DB_Master_Out"
  STRUCT
    SendData : ARRAY[1..70] OF INT;   // 140 bytes
    RecvData : ARRAY[1..40] OF INT;   //  80 bytes
    Status   : DWORD;                 // PUT/GET return codes
  END_STRUCT
END_DATA_BLOCK

5.2 Slave DB (DB200, slave CPU)

DATA_BLOCK "DB_Slave_In"
  STRUCT
    RecvData : ARRAY[1..70] OF INT;   // mirror of master SendData
    SendData : ARRAY[1..40] OF INT;   // mirror of master RecvData
    Heartbeat : BOOL;                 // toggle each scan
  END_STRUCT
END_DATA_BLOCK

Symbolic access on both sides makes the PUT/GET address specification readable.

6. PUT/GET Programming

In TIA Portal, the blocks are called PUT and GET. In STEP 7 V5.x they are FB 15 PUT and FB 14 GET, located in the Standard Library → Communication Blocks.

6.1 OB1 of the master CPU — send (PUT) and receive (GET)

// Cyclic call at OB1 scan rate. Rising edge on REQ triggers one transfer.
// Use a 1 Hz clock flag (e.g., M10.5 from clock memory) on REQ.

CALL  "PUT" , DB15
   REQ     := M10.5
   ID      := W#16#1            // connection ID from NetPro
   DONE    := M100.0
   ERROR   := M100.1
   STATUS  := MW102
   ADDR_1  := P#DB200.DBX 0.0 BYTE 80       // slave: first 80 bytes (40 INT)
   ADDR_2  := P#DB200.DBX 80.0 BYTE 0       // no second area
   SD_1    := P#DB100.DBX 0.0 BYTE 140      // master: send 70 INT
   SD_2    := P#DB100.DBX 140.0 BYTE 0     // not used
   LEN     := 140                          // total payload bytes
   // SD_3, SD_4, ADDR_3, ADDR_4 omitted for S7-300
;

CALL  "GET" , DB14
   REQ     := M10.5
   ID      := W#16#1
   DONE    := M101.0
   ERROR   := M101.1
   STATUS  := MW104
   ADDR_1  := P#DB200.DBX 0.0 BYTE 80       // read first 40 INT from slave
   ADDR_2  := P#DB200.DBX 80.0 BYTE 0       // not used
   RD_1    := P#DB100.DBX 140.0 BYTE 80     // write to RecvData area
   RD_2    := P#DB100.DBX 220.0 BYTE 0     // not used
   LEN     := 80
;

6.2 Parameter table

7. Alternative Path: FETCH/WRITE via Open Communication Wizard

If the PUT/GET path is unavailable because the slave CPU is in a remote rack or because the application requires FETCH/WRITE semantics (RFC 1006 over ISO-on-TCP), use the Open Communication Wizard from Siemens. This generates the connection DB and parameterises FB 8 USEND, FB 9 URCV, FB 10 FETCH (FB 11 FETCH_R) and FB 12 WRITE for ISO-on-TCP (port 102).

1. Install Open Communication Wizard from the STEP 7 DVD or the Siemens support portal.
2. Select Fetch/Write with connection type ISO-on-TCP.
3. Wizard generates DBs (e.g., DB300) containing the connection description: REM_STADDR, TSAP_ID_LEN, TSAP_ID, partner IP.
4. Call FB 11 FETCH_R in OB35 with cycle of 100 ms; the slave CPU returns data from the requested DB area.

Use FETCH/WRITE only when PUT/GET is explicitly disabled by the slave protection configuration or when integrating to a third-party S7 client.

8. Connection Resource Accounting

The S7-315-2 PN/DP reserves a finite number of connection resources. For FW V3.3:

The S7-300 does not dynamically assign connection resources; every reserved resource reduces available OP/PG slots. Plan ahead: each PUT/GET pair to a unique slave uses one S7 connection. With eight slaves, you consume eight S7 connections.

9. Download and Online Test

1. Download hardware configuration to both CPUs (PLC → Download to Target Station).
2. Download the program (OB1, DB100, DB15, DB14) to the master, and DB200 + OB1 (slave logic) to the slave.
3. Switch both CPUs to RUN.
4. Open the master online with Monitor/Modify on DB100. Set values in SendData[1..70].
5. On the slave, open DB200 online; RecvData[1..70] should mirror within 1 second (clock period of M10.5).
6. Modify DB_Slave_In.SendData[1..40] on the slave; the master DB100 RecvData should reflect the change.

10. Diagnostics and Verification

Use the diagnostic buffer (PLC → Diagnostic Buffer) on both CPUs. For deeper inspection, evaluate the STATUS word of PUT/GET blocks. Common return codes:

Verify IP reachability first: from the master engineering station, ping 192.168.0.20. A time-out indicates a switch, cabling, or IP-misconfiguration issue rather than a programming fault. Then use NetPro's Check Connection (right-click the connection → Connection Status).

11. Troubleshooting Matrix

12. Performance and Timing Considerations

PUT/GET on the S7-315-2 PN/DP uses the standard S7 communication stack. Typical transfer times:

Calling PUT/GET faster than the transfer time causes STATUS = 7002 (job still active). Use a 100 ms or 1 s clock on REQ for non-time-critical data. For sub-10 ms determinism, switch to PROFINET IO real-time (IRT) with slot-based data exchange — but that requires a PROFINET IO device on the slave side and is out of scope for this S7-only PUT/GET path.

13. Commissioning Checklist

• ☐ IP addresses assigned and reachable (PING).
• ☐ Slave CPU protection permits PUT/GET.
• ☐ Partner DB exists on slave, non-optimised, byte-aligned, correct length.
• ☐ Connection configured in NetPro / TIA "Connections" with valid local ID.
• ☐ ID parameter of PUT/GET matches the local connection ID (W#16#1 or TIA symbolic ID).
• ☐ LEN ≤ 160 bytes, even number.
• ☐ REQ edge generated at acceptable rate.
• ☐ DONE / ERROR / STATUS monitored.
• ☐ Connection resource budget reviewed.
• ☐ Diagnostic buffer free of new entries after download.

14. Frequently Asked Questions