Do Modern Industrial PCs Still Have a Parallel Port?

The parallel port disappeared from consumer motherboards a decade ago. It never disappeared from the factory floor.

CNC controllers, EPROM programmers, older test and measurement benches, label printers and software licence dongles were all built around IEEE 1284. The equipment outlived the interface. When the PC driving one of those machines finally dies, the problem is rarely the application — it is finding a current computer that still has somewhere to plug it in.

Why a USB-to-parallel adapter usually is not the answer

This is the fix most people try first, and it is the reason they end up calling us.

A USB-to-parallel adapter presents itself to the operating system as a USB printer class device. It does not create a port at a real I/O address, and it gives software no direct register access. Anything that expects to talk to LPT1 the old way will not see it:

• Legacy DOS and early Windows software that writes directly to the port address
• Timing-sensitive control loops that toggle individual pins
• Custom drivers written against the hardware rather than against a print spooler
• Licence dongles that probe the port directly

If the application was written to print to a printer, an adapter is usually fine. If it was written to control something, it usually is not.

How DuroPC provides a parallel port

The parallel port is integrated in the main chipset and accessed through an onboard pin header, which we bring out to a standard DB25 connector on a rear I/O bracket. It is the board's own port, at the address software expects — not an emulated one. The same bracket commonly carries the DB9 serial port, which is the other interface these installations tend to need.

The standard base I/O addresses for a parallel port are 0x378 (LPT1), 0x278 (LPT2) and 0x3BC. Software written against the hardware expects to find the port at one of these — which is exactly what a USB adapter cannot present.

IEEE 1284 defines several operating modes, and which of them are available depends on the specific board and its BIOS settings. Tell us what the port has to talk to and we will confirm the supported modes on the exact machine before you order, rather than after.

Industrial computers with a parallel port

Every machine below lists a parallel port in its own specification, and most offer the I/O bracket as a priced build option:

• R160-209 — 1U rackmount, for a standard cabinet
• S810-4P2I — 4x PCI and 3x ISA, for the oldest card sets
• SHB160-105 and SHB160-109 — 6-slot backplane systems
• SHB160-110, SHB160-111, SHB160-116 and SHB160-208 — 8-slot backplane systems

If the machine you need is not on this list, ask anyway — the port is frequently available as a build option on other models.

Tell us what it has to connect to

The useful conversation is not about the computer, it is about the equipment on the other end of the cable. Tell us what the parallel port has to drive and which operating system the software needs, and we will confirm exactly what is required before anything ships. Get in touch or request a quote.