Siemens Field PG and PC Adapter Selection for S7-300, S7-200

Overview

An automation engineer maintaining a heterogeneous Siemens fleet — for example, an S7-300 CPU 315-2 PN/DP, an S7-200 CPU 226, a MP 377 HMI, a Sinamics G120 drive, and a Sinamics GM150 with CU320 — must solve a programming-hardware selection problem that crosses three decades of Siemens product generations. Each device family uses a different native bus (PPI, MPI, PROFIBUS, PROFINET, RS-485 Modbus RTU, and drive-specific USS/PROFIdrive), and each Siemens engineering tool (STEP 7 V5.x, STEP 7 Micro/WIN, WinCC flexible, STARTER, and TIA Portal) has its own runtime, port, and OS footprint. Choosing the wrong programming console, the wrong PC adapter, or the wrong cable means the engineer cannot reach one or more devices on the bench or on the plant floor.

This reference consolidates the device-to-adapter mapping, the obsolete/active status of the legacy PC Adapter USB, the current successor, and the practical commissioning layout (hard-disk partitions, OS choice, software stack) recommended for an engineer who must service exactly the fleet listed above. All part numbers, software catalog references, and bus standards correspond to the official Siemens Industry Online Support product tree and the PROFIBUS/PROFINET International (PI) standards catalog.

Programming Hardware: Field PG vs. Industrial Notebook vs. Office Notebook

A Siemens Field PG (programmer device, German: Programmiergerät) is the factory-preinstalled industrial programming console Siemens ships for service work on SIMATIC, SINAMICS, and SIMOTION hardware. The current generation is the SIMATIC Field PG M6 (catalog suffix 6ES7718-...) — a ruggedized laptop with preinstalled SIMATIC software, MPI/PROFIBUS interface, PROFINET interface, and an SD card slot for SIMATIC Memory Cards.

For an engineer who commissions a plant containing an S7-300, an S7-200, and a Sinamics drive family simultaneously, the Field PG pays for itself in the elimination of driver, port, and licensing friction. For budget-constrained setups, a ruggedized third-party industrial notebook running the same Siemens-tested Windows IoT LTSC image is acceptable.

Legacy PC Adapter USB A2 (6ES7972-0CB20-0XA0) — Phased Out

The PC Adapter USB A2, catalog number 6ES7972-0CB20-0XA0, was the canonical Siemens accessory for connecting a programming PC to a SIMATIC S7 PLC over MPI or PROFIBUS from a USB 2.0 host. It contained an RS-485 transceiver, an MPI/PROFIBUS firmware stack (loaded from the Siemens CD at first plug-in), and a 5-meter USB cable in the box.

Spare units still appear in the second-hand market, but Siemens Industry Online Support no longer maintains the firmware, and Windows 10/11 cumulative updates periodically break the legacy Siemens PC-Adapter USB NDIS driver. New builds should specify the successor described next.

Successor: CP 5711 USB Adapter (6GK1571-0BA00-0AA0)

The successor to the PC Adapter USB A2 is the SIMATIC CP 5711, catalog number 6GK1571-0BA00-0AA0. It is a USB-2.0-to-MPI/PROFIBUS communications processor that offloads the PROFIBUS DP-V0/V1 line discipline into hardware. Unlike the PC Adapter USB A2, the CP 5711 does not require a CD-loaded firmware driver at first use; it installs as a standard Windows network class device and is recognized by STEP 7, TIA Portal, and STARTER without per-application configuration.

The CP 5711 is the default recommendation for any new S7-300 / S7-400 / Sinamics commissioning build. For PROFINET-only devices (S7-1500, ET 200SP, MP 377), no bus adapter is needed — a standard GbE NIC on the programming PC, with TCP/IP routing, is sufficient.

Communication Adapter Reference Matrix

The following table maps every device family in the engineering scope to the correct programming adapter, cable, and connector. Each row corresponds to a real Siemens catalog entry; verify the live status against the Siemens Industry Online Support product tree before procurement.

PC/PPI cable for S7-200 (6ES7901-3DB30-0XA0)

The PC/PPI cable (also historically called the PC/PPI USB Multi-Master Cable) is the correct tool for an S7-200 CPU 226 in PPI mode. It draws 5 V from the S7-200 port to power the RS-485 transceiver, so it does not require an external power supply. Supported baud rates on PPI are 9.6 kbit/s and 19.2 kbit/s by default; STEP 7 Micro/WIN can negotiate higher PPI baud rates up to 187.5 kbit/s.

Configuration switch positions on the PC/PPI cable:

1. Switch 1: ON = PPI/Freeport multi-master; OFF = PPI single-master.
2. Switches 2–4: Baud rate selector (010 = 9.6 kbit/s, 011 = 19.2 kbit/s, 100 = 187.5 kbit/s, 101 = 187.5 kbit/s adaptive).
3. Switch 5: ON = PPI/Freeport; OFF = PPI only (legacy compatibility).
4. Switch 6: ON = Remote address mode (RS-232 echo); OFF = normal.

Software Stack per Device Family

Each Siemens device family requires a specific engineering tool, and the tools are not fully interchangeable. The complete stack to service the fleet listed above is shown below.

Hard-Drive Partition and OS Isolation Strategy

Two software conflicts dominate Siemens-classic engineering:

1. STEP 7 V5.x and STEP 7 Micro/WIN share the Siemens PLC Driver NDIS service. Installing both on the same Windows user profile produces COM-port conflicts and PC Adapter enumeration failures.
2. STARTER 5.4 SP3 and TIA Portal V18 cannot share the same installed instance of the S7PCT (Port Configuration Tool). They must be installed on separate Windows installations or isolated via separate user profiles and separate PATH entries.

The recommended layout for a single Field PG or industrial notebook supporting the entire fleet:

Boot selection between partitions is handled by the standard Windows Boot Manager; this is the lowest-risk approach. A single OS with three user profiles is acceptable but requires careful PATH and registry-key isolation.

Connectivity to the S7-200 CPU 226 (PPI)

The CPU 226 exposes two RS-485 ports. Port 0 is the PPI/multi-master port; Port 1 can be configured as PPI, MPI, Freeport, or Modbus RTU master.

1. Connect the PC/PPI cable (6ES7901-3DB30-0XA0) to Port 0 of the CPU 226.
2. Set the cable switches: 1=ON, 2=OFF, 3=OFF, 4=ON (9.6 kbit/s, PPI multi-master), or 1=ON, 2=ON, 3=OFF, 4=ON (19.2 kbit/s).
3. Plug the USB end into the engineering station; Windows installs the FTDI-based cable driver automatically.
4. In Micro/WIN, set the communications interface to PC/PPI cable (PPI) and address 2 (the CPU 226 default).
5. Click Communicate > Read/Write CPU; the project should appear within 2–5 s at 9.6 kbit/s.

Connectivity to the S7-300 CPU 315-2 PN/DP

The 315-2 PN/DP exposes both a PROFIBUS DP port (X2, Sub-D 9) and a PROFINET port (X1, RJ45). Choose the bus based on the existing plant topology:

• PROFINET path (preferred for new builds): Connect the engineering station's GbE NIC directly to the X1 port (crossover or via a 1-port switch). In STEP 7 / TIA Portal, set the PG/PC interface to S7ONLINE → TCP/IP <your NIC>. Assign an IP address (e.g., 192.168.0.10/24) compatible with the CPU's PROFINET interface (default 0.0.0.0/0 — first connection must be made through the MPI/PROFIBUS port to assign IP).
• PROFIBUS path: Connect the CP 5711 to the X2 port. In STEP 7, set the PG/PC interface to PC Adapter (PROFIBUS). The CP 5711 auto-detects baud rate from 9.6 kbit/s to 12 Mbit/s.
• MPI path (legacy): Set the CP 5711 to MPI mode (bus speed 187.5 kbit/s). Use this only when the X2 port is already configured as MPI master and the PROFIBUS DP network is not reachable.

For first-time commissioning of a CPU with default IP 0.0.0.0, you must use the CP 5711 over MPI to assign the PROFINET IP. TIA Portal cannot reach an unaddressed PROFINET device over Ethernet.

Connectivity to the Sinamics G120 / GM150

The G120 (CU240E-2 PN or CU250S-2 PN) and the GM150 with CU320 are PROFINET-capable, but the GM150 retains a strong PROFIBUS service path because its commissioning tool (STARTER) has not been fully migrated into TIA Portal Startdrive. The drive configuration workflow is:

1. Identify the Control Unit's PROFINET device name (e.g., g120-cu240e2). The factory default is blank — the device is not reachable by name until one is assigned.
2. Connect the engineering station to the drive's PROFINET port. Use TIA Portal's Online > Accessible Nodes or STARTER's Accessible Nodes to detect the drive by MAC address.
3. Assign the PROFINET device name from TIA Portal Online > Assign PROFINET Device Name, or from STARTER Online > Accessible Nodes > Edit PROFINET Device Name.
4. Restart the drive (power cycle or reset via STARTER) so the new name takes effect.
5. Establish an online connection; upload or download the parameter set as required.

For GM150 with CU320, prefer STARTER 5.4 SP3 HF1 over PROFINET at 100 Mbit/s full-duplex. The CU320 supports DRIVE-CLiQ for internal sub-modules (Sensor Modules, Terminal Modules, Motor Modules) but DRIVE-CLiQ is not a programming bus — it is the internal real-time drive-to-drive link.

Connectivity to the MP 377 HMI

The MP 377 (12" or 15" key/touch variants) is a WinCC flexible Runtime panel with PROFINET and PROFIBUS interfaces. Two commissioning paths are common:

• Ethernet transfer (preferred): In WinCC flexible 2008 SP5 (or TIA Portal WinCC Professional), select Transfer > Ethernet. Configure the MP 377's PROFINET port IP (default 192.168.0.20, mask 255.255.255.0), put the panel into transfer mode (service touch sequence on the HMI screen), and download the compiled HMI runtime.
• PROFINET IRT with S7-300: When the MP 377 is part of an S7-300 PROFINET subnet with isochronous IRT (e.g., coordinated with a SIMOTION controller), configure the topology in TIA Portal. The MP 377 supports IRT only on certain firmware revisions (firmware V12.0.0+); verify the firmware version before commissioning.

Connectivity to the Sicostar Soft Starter

The Sicostar (now sold as Sirius 3RW) is a soft-starter family supporting Modbus RTU over RS-485. Programming access typically uses the Sirius Engineering Tool or direct Modbus RTU register reads/writes from any standard Modbus master (e.g., a PC with a USB-to-RS485 converter).

1. Wire the Sicostar's RS-485 terminals (D+, D-, GND) to a shielded twisted-pair bus. Apply 120 Ω termination at both physical ends of the bus.
2. Configure the Sicostar's Modbus address (default 1, configurable via the operator panel on the device front).
3. From the engineering station, use a USB-to-RS485 converter. Many Siemens application notes reference the Siemens 6SL3555-0PA00-0AA0 USB/RS485 PC cable as the approved converter; third-party converters based on FTDI FT232R + isolated RS-485 transceiver (e.g., ADM2582E) also work reliably.
4. Open the Sirius Engineering Tool, set COM port to 19200 bit/s, 8 data bits, even parity, 1 stop bit (Modbus RTU default for Sirius), and address 1.
5. Upload the parameter set; verify by reading register 100 (device status word) — it should return 0x0001 (Ready).

Cabling and Connector Reference

Selection Matrix and Recommendations

Verification Checklist

1. Field PG or industrial notebook boots cleanly on all three partitions (TIA, STEP 7 classic, Micro/WIN). Verify no driver conflict in Device Manager across boots.
2. CP 5711 enumerates as Siemens CP 5711 (PROFIBUS) in Device Manager on the STEP 7 classic partition. Verify TIA Portal and STARTER also recognize it on their respective partitions.
3. Connect CP 5711 to S7-300 X2; in STEP 7, Accessible Nodes returns the CPU 315-2 PN/DP within 5 s.
4. Connect PC/PPI cable to CPU 226; in Micro/WIN, Communicate returns the project tree within 5 s.
5. Connect GbE NIC to S7-300 X1 (after IP assignment via MPI); TIA Portal Accessible Nodes returns the CPU via TCP/IP.
6. Connect GbE NIC to MP 377 PROFINET; WinCC flexible or TIA WinCC Transfer → Ethernet succeeds within 30 s.
7. Connect CP 5711 or GbE NIC to G120 / GM150; STARTER Accessible Nodes returns the drive by PROFINET name or PROFIBUS DP address.
8. Connect USB-RS485 to Sicostar; Sirius ET reports device status 0x0001 (Ready) within 2 s.

Troubleshooting Matrix

Field Commissioning Notes

• Always record the CP 5711 firmware version, the TIA Portal installation version, and the STARTER version on the project handover document. Siemens service bulletins are often tied to specific (tool, firmware) pairings.
• For first-time IP assignment on an S7-300 with default 0.0.0.0, plan an MPI path on the CP 5711. Trying to assign IP over Ethernet on an unaddressed device fails silently.
• When commissioning a Sinamics G120 or GM150 alongside an S7-300, configure the drive's PROFINET device name before configuring the S7-300's PROFINET IO table. Otherwise the IO assignment will fail on first download and the engineer will chase a phantom configuration error.
• For a multi-engineer team, centralize STEP 7, TIA Portal, and STARTER licenses on a Siemens license server (Automation License Manager) instead of node-locked licenses. Floating licenses remove the per-seat friction that delays plant commissioning.
• Keep a verified-good spare CP 5711 and PC/PPI cable in the site kit. Both are field-failure items: the CP 5711 Sub-D 9 connector wears with repeated plug cycles, and the PC/PPI cable's internal fuse (5 V supply from the CPU) can blow if the CPU's 24 V supply rail is shorted.