Siemens / SIMATIC S7-300 / CPUs, power supplies and interface modules

Every S7-300 CPU article number, standard, compact, fail-safe, technology and C7. Plus the PS 307 supplies and IM rack expansion modules.

The CPU is the expensive part and the one people most often get wrong when ordering a replacement, because Siemens made a lot of versions of the same CPU and they are not all interchangeable.

Read this before you order a CPU

The CPU 319 has a 6ES7318 article number

Both the CPU 319-3 PN/DP and the CPU 319F-3 PN/DP carry article numbers beginning 6ES7318, not 6ES7319. If you have searched 6ES7319 and found nothing, that is why. The part exists.

The version digits are not cosmetic

Take 6ES7315-2AH14-0AB0. The characters before the final block identify the generation. Earlier versions of the same CPU exist and Siemens writes them with an x as a wildcard, for example 6ES7315-2AF0x-0AB0.

Different versions of the same CPU are not always interchangeable. Firmware level affects which STEP 7 or TIA Portal version can configure them and which functions are supported. Read the number off the module, never off the drawing.

Memory card and battery

Later S7-300 CPUs use a SIMATIC Micro Memory Card, article numbers beginning 6ES7953, and the card is not optional. A CPU supplied without one will not run the user program. If you buy a used CPU from anyone and it will not start, this is the first thing to check.

Earlier CPUs use a lithium backup battery to retain memory. Siemens rates the shelf life of that battery at five years, so a CPU that has sat in a warehouse for a decade may arrive flat. We check this before shipping.

Standard CPUs

Compact CPUs

Onboard I/O built in. Popular on small machines, and when one fails the whole unit has to be replaced.

Fail-safe CPUs

These carry safety approvals. A plant running a safety function cannot substitute a standard CPU for one, whatever the price difference.

Technology CPUs

Motion control variants. Low volume, high value, and almost nobody carries them.

C7 all-in-one units

CPU and operator panel in one housing. Long discontinued, no direct replacement, and when one dies the machine stops.

Power supplies

The PS 305 takes a DC input of 24, 48, 72, 96 or 110 V DC, range 16.8 to 138 V DC, rather than mains AC. That makes it the one to reach for on battery backed or DC distribution systems, and people specifically hunt for it.

Parallel wiring. The PS 307 2 A and 5 A support it. The 6ES7307-1EA80-0AA0 variant does not. Worth knowing if a supply is undersized.

Interface modules for rack expansion

These are ordered as matched pairs. Getting the pairing wrong is a common ordering mistake, so tell us how many racks you are running and we will get it right.

SIPLUS CPU equivalents

Extended environmental range. The EN 50155 versions are rail approved, which is a separate and quite specific market.

Send us your article numbers

Read the full number off the front of the CPU including the suffix, and tell us whether you have the memory card. We will come back with price, condition and lead time. Quotes in NZD including GST.

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Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Siemens AG. All trademarks, brand names and article numbers are the property of their respective owners and are used here for identification purposes only.