Siemens S7-300 Parts NZ | Obsolete Modules & CPUs

Siemens SIMATIC S7-300 Parts

Siemens / SIMATIC S7-300

Discontinued by Siemens, still running half the plant in New Zealand. Send us the article number.

The SIMATIC S7-300 is out of production. It is also still in service across dairy, pulp and paper, food processing, water and power generation right across the country, because it works and because migrating a running plant is expensive.

That means when a module fails, there is no new supply through official channels. A like-for-like replacement comes from the secondary market: unused stock that was never installed, surplus from decommissioned plant, and tested used modules. That is what we do.

Every article number below is taken from the Siemens S7-300 Module Data equipment manual. Send us the number off the front of the module and we will tell you the same day whether we can get it and what it costs.

Module groups

Group	Article numbers start	What it does
CPUs	6ES7 312 to 319	Standard, compact, fail-safe and technology CPUs
SM 321 digital input	6ES7 321	Reads switches, proximity sensors, contacts
SM 322 digital output	6ES7 322	Drives solenoids, contactors, lamps. Transistor and relay
SM 323 / SM 327 combined	6ES7 323 / 327	Input and output on one module
SM 331 analog input	6ES7 331	Voltage, current, RTD and thermocouple
SM 332 analog output	6ES7 332	Drives valves, drive references, indicators
SM 334 analog combined	6ES7 334	Analog in and out on one module
SM 338 position decoder	6ES7 338	SSI encoder input
PS 307 / PS 305 power supplies	6ES7 307 / 305	2 A, 5 A and 10 A
IM 360 / 361 / 365	6ES7 360 / 361 / 365	Rack expansion interface modules
CP communication	6ES7 340 to 343	Serial, PROFIBUS, Ethernet
FM function modules	6ES7 350 to 355	Counting, positioning, closed loop control
Front connectors	6ES7 392	20-pin and 40-pin, screw and spring
Memory cards	6ES7 953	SIMATIC Micro Memory Card

Three things that catch people out

Modules ship without a front connector

Siemens supplies S7-300 signal modules bare. The front connector is a separate article number and it is the single most common thing left off an order.

Article number	Connector
6ES7392-1AJ00-0AA0	20-pin, screw terminals
6ES7392-1AM00-0AA0	40-pin, screw terminals
6ES7392-1BM01-0AA0	40-pin, spring terminals

The 64-channel modules use two 40-pin blocks, not one. Tell us the module and we will include the right connector in the quote.

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 search 6ES7319 and find nothing, that is why.

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.

Earlier CPUs use a lithium backup battery to retain memory. Siemens rates the shelf life of that battery at five years, so a used CPU that has sat in a warehouse may well arrive with a flat one. We check this before shipping and tell you what you are getting.

Not every module reports a fault

Only some S7-300 modules have programmable diagnostics. On the digital output side that is 6ES7322-8BH10-0AB0, 6ES7322-5GH00-0AB0, 6ES7322-8BF00-0AB0, 6ES7322-5FF00-0AB0 and 6ES7322-5HF00-0AB0. The rest fail silently.

This matters when substituting. Two modules that look identical on paper can differ on diagnostics, and swapping one for the other means the CPU configuration no longer matches and the engineer loses fault reporting. A clear example is the relay pair 6ES7322-1HF10-0AA0 and 6ES7322-5HF00-0AB0. Both are 8 x relay at 230 V AC / 5 A. Only the 5HF00 has diagnostics, a diagnostic interrupt and substitute value output.

If you are not sure whether a substitute will work, send us both numbers and we will tell you.

Protect your output modules

S7-300 digital output modules have integrated overvoltage protection, but Siemens is clear that external suppression is still needed in two cases: where an output circuit can be broken by an added contact such as a relay, and where the inductive load is not switched by a SIMATIC module.

Use a diode or Zener diode across DC coils, and a varistor or RC element across AC coils. Unsuppressed contactor coils are a common cause of output module failure, and if the replacement goes into the same circuit it will fail the same way.

ET 200M uses the same modules

An ET 200M station is an IM 153 interface module plus ordinary S7-300 signal modules on a standard rail. If you are chasing a module for a distributed rack rather than a central one, everything on this page applies.

If you are migrating

The S7-1500 is the successor platform, but it is not a drop-in. Different rack, different power supply, new front connectors, and a hardware reconfiguration in TIA Portal. Budget it as a project rather than a spare part.

If the line is down tonight, source the original. If you are planning a changeover, we can supply the new hardware, keep the old system running through commissioning, and take the decommissioned racks away afterwards.

Send us your article numbers

One module or a full project list. We will come back with price, condition and lead time. Quotes in NZD including GST.

Request a quote

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.