To request the right Siemens S7-300 replacement, collect the full order number, hardware or firmware details, required condition and delivery deadline. A description such as “S7-300 CPU” or “digital input module” is useful context, but it is not enough to identify the part to buy.
This checklist helps maintenance teams and purchasing departments prepare a clear enquiry and compare offers without losing important technical details.
What the S7-300 lifecycle means for buyers
Siemens identifies 1 October 2025 as the S7-300 / ET 200M product cancellation milestone (PM410), followed by a spare-parts phase planned until 1 October 2033. Siemens also notes that single components can have earlier dates.
Source: Siemens, SIMATIC PCS 7 Remote I/O Upgrade Guideline (entry 109824203), section 1.1 Product Lifecycle.
This is a family-level support plan, not a guarantee that every order number will be available when you need it. Check the exact product’s current status and obtain a quotation for the requested quantity and destination. The status of each order number we have researched is in the S7-300 lifecycle database.
1. Capture the complete Siemens order number
Copy every character from the label, including all suffixes. Siemens order numbers are also commonly referred to as MLFB numbers. Attach a clear photograph so the supplier can check your transcription.
Record the description separately from the order number. For example, “CPU 314” describes a product type; the complete reference on the unit identifies the specific item being requested.
Use the installed equipment, engineering records and bill of materials together. If those sources disagree, resolve the discrepancy with the responsible engineer before approving a purchase. A supplier should not have to guess which reference is authoritative.
2. Record revision details and application requirements
For a CPU, capture the hardware and firmware information available on the label or in the engineering system. For an I/O module, record the exact reference and any revision requirement specified by the application owner.
Ask the engineer to identify constraints that an offered alternative must meet. Relevant checks may include the signal type, electrical characteristics, channel count, interface, connections and project configuration. This list is a starting point for review, not a declaration that matching these features proves compatibility.
If a supplier proposes another order number, request a written explanation of the proposed substitution. Have the application owner approve it before purchase.
3. Define the condition you will accept
TIMC quotes new factory sealed, new surplus or new without box as standard, and can source used or refurbished units when a buyer needs them. Offers for legacy parts may use condition terms differently, so ask the seller to describe the actual unit and supporting evidence rather than relying on a short label.
| Offered condition | Questions to include in the enquiry |
|---|---|
| New: factory sealed, new surplus or new without box | Is it unused? What packaging, label photographs and provenance information are available? |
| Refurbished | What work was performed? What testing was completed, and is a report available? |
| Used | What is the stated operating condition? What inspection or test evidence supports it? |
| Any acceptable condition | Which conditions can be quoted separately, with their respective prices and terms? |
Confirm warranty duration, coverage, exclusions and the return process in writing. Check who provides the warranty; do not assume an independent distributor’s offer carries the manufacturer’s warranty.
4. Confirm what is included
A quotation for a module may not cover everything required to install or commission it. List any accessories you need, such as front connectors, memory cards or interface connectors, and request that they appear as explicit line items.
For a CPU replacement, ask your engineering team how the program, configuration and any required memory media will be handled. Establish those responsibilities before placing the order so the delivered hardware does not arrive without a commissioning plan.
5. Compare replacement and migration scopes
An exact-part replacement request aims to maintain the existing installation. Moving to a different platform requires a broader review.
Siemens publishes a guide for migrating S7-300/S7-400 to S7-1500, covering hardware and software considerations. A platform identified as a successor should be treated as a migration candidate until the application’s requirements have been assessed. The guide is an older reference; check current documentation for the selected hardware and software versions.
| Situation | Useful next step |
|---|---|
| Urgent fault with a known reference | Request an exact-part quote and plan restoration with the controls engineer. |
| Exact part unavailable | Request documented alternatives and review compatibility before purchase. |
| Repeated faults or a scheduled upgrade | Assess a migration project, including engineering, installation and commissioning. |
| Critical spare for an operating machine | Define the required condition, revision, storage and future verification plan. |
6. Send an RFQ the supplier can act on
Use this enquiry template:
Please quote the following Siemens S7-300 part:
Complete order number:
Quantity:
Hardware revision / firmware, if applicable:
Required condition / acceptable alternatives:
Required accessories:
Delivery destination:
Required on-site date:
Label photographs attached:
Please confirm the offered reference, condition, price, lead time, warranty terms and any exceptions to our requirements. Please quote alternatives separately for engineering approval.
Compare quotations against the same requirements. Distinguish dispatch timing from the expected delivery date and clarify freight arrangements before ordering.
Request a Siemens S7-300 quotation
Browse TIMC’s SIMATIC S7-300 family or send the complete order number, quantity and a label photograph with the quote form. TIMC sources current, surplus and discontinued components. Availability, offered condition, lead time and warranty terms are confirmed in the quotation. TIMC is an independent distributor and is not authorized by Siemens.
