Siemens SM 322 Digital Output & Relay Modules | S7-300

Siemens SM 322 Digital Output Modules

Every SM 322 variant, transistor and relay, plus the SM 323 and SM 327 combined modules. Twenty-one article numbers on one page.

The SM 322 is the digital output module family for the SIMATIC S7-300 rack. It drives solenoid valves, contactors, motor starters and indicator lamps. Variants split into transistor outputs and relay outputs, and differ by channel count, current rating, load voltage and whether diagnostics are supported.

Output modules fail more often than input modules, because they switch inductive loads. Siemens discontinued the S7-300 platform, so replacements come from the secondary market. We hold some of these lines and source the rest.

SM 322 transistor output modules

Article number	Description	Outputs	Current	Load voltage	Isolation	Diagnostics
6ES7322-1BP00-0AA0	DO 64 x DC 24 V/0.3 A, sourcing	64	0.3 A	24 V DC	groups of 16	No
6ES7322-1BP50-0AA0	DO 64 x DC 24 V/0.3 A, sinking	64	0.3 A	24 V DC	groups of 16	No
6ES7322-1BL00-0AA0	DO 32 x DC 24 V/0.5 A	32	0.5 A	24 V DC	groups of 8	No
6ES7322-1FL00-0AA0	DO 32 x AC 120/230 V/1 A	32	1.0 A	120/230 V AC	groups of 8	No
6ES7322-1BH01-0AA0	DO 16 x DC 24 V/0.5 A	16	0.5 A	24 V DC	groups of 8	No
6ES7322-1BH10-0AA0	DO 16 x DC 24 V/0.5 A, High Speed	16	0.5 A	24 V DC	groups of 8	No
6ES7322-8BH10-0AB0	DO 16 x DC 24 V/0.5 A, programmable	16	0.5 A	24 V DC	groups of 4	Yes
6ES7322-5GH00-0AB0	DO 16 x UC 24/48 V	16	0.5 A	24 to 48 V AC/DC	groups of 1	Yes
6ES7322-1FH00-0AA0	DO 16 x AC 120/230 V/1 A	16	1 A	120/230 V AC	groups of 8	No
6ES7322-1BF01-0AA0	DO 8 x DC 24 V/2 A	8	2 A	24 V DC	groups of 4	No
6ES7322-8BF00-0AB0	DO 8 x DC 24 V/0.5 A, diagnostic interrupt	8	0.5 A	24 V DC	groups of 8	Yes
6ES7322-1CF00-0AA0	DO 8 x DC 48 to 125 V/1.5 A	8	1.5 A	48 to 125 V DC	groups of 4, reverse polarity protected	No
6ES7322-1FF01-0AA0	DO 8 x AC 120/230 V/2 A	8	2 A	120/230 V AC	groups of 4	No
6ES7322-5FF00-0AB0	DO 8 x AC 120/230 V/2 A, ISOL	8	2 A	120/230 V AC	groups of 1	Yes

SM 322 relay output modules

These are the ones that wear out, because relay contacts have a finite operation count.

Article number	Description	Outputs	Load voltage	Isolation	Diagnostics
6ES7322-1HH01-0AA0	DO 16 x relay, AC 120/230 V	16	24 to 120 V DC, 48 to 230 V AC	groups of 8	No
6ES7322-1HF01-0AA0	DO 8 x relay, AC 230 V	8	24 to 120 V DC, 48 to 230 V AC	groups of 2	No
6ES7322-1HF10-0AA0	DO 8 x relay, AC 230 V/5 A	8	24 to 120 V DC, 48 to 230 V AC	groups of 1	No
6ES7322-5HF00-0AB0	DO 8 x relay, AC 230 V/5 A	8	24 to 120 V DC, 24 to 230 V AC	groups of 1	Yes

The 1HF10 and 5HF00 are not interchangeable

Both are 8 x relay at 230 V AC / 5 A. They look like the same part and they are not.

The 6ES7322-5HF00-0AB0 has programmable diagnostics, a diagnostic interrupt and substitute value output. The 6ES7322-1HF10-0AA0 has none of those. Replace a 5HF00 with a 1HF10 and the plant loses diagnostics on those channels, and the CPU hardware configuration no longer matches what is in the rack.

If you are not sure which one you have, send us the number and we will tell you.

SM 323 and SM 327 combined modules

Article number	Description	Inputs	Outputs	Current
6ES7323-1BL00-0AA0	DI 16 / DO 16 x DC 24 V/0.5 A	16	16	0.5 A
6ES7323-1BH01-0AA0	DI 8 / DO 8 x DC 24 V/0.5 A	8	8	0.5 A
6ES7327-1BH00-0AB0	DI 8 / DX 8 x DC 24 V/0.5 A, programmable	8	8 configurable as input or output	0.5 A

The SM 327 is worth knowing about. Its eight channels can each be configured as input or output, and inputs can be read back for diagnostics. That makes it a useful substitute when a specific SM 321 or SM 322 cannot be found, which is exactly the situation most people are in on this platform.

Only five of eighteen report faults

Of all the SM 322 variants, only 6ES7322-8BH10-0AB0, 6ES7322-5GH00-0AB0, 6ES7322-8BF00-0AB0, 6ES7322-5FF00-0AB0 and 6ES7322-5HF00-0AB0 have programmable diagnostics. The rest fail silently.

On modules that do report, the SF group fault LED lights when a diagnostic message is raised and goes out once every fault condition clears. It also lights for external faults such as a short circuit on the sensor supply, regardless of what state the CPU is in.

Before you condemn a module, check the fuse

The 6ES7322-1FF01-0AA0 has a blown fuse indicator and a replaceable fuse per group. A module written off as dead may only need a fuse.

Why output modules fail, and how to stop it happening again

S7-300 digital output modules have integrated overvoltage protection. Siemens is clear that this is not always enough, and that external suppression is still required in two cases: where a SIMATIC 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 at all.

For DC coils, fit a diode or a Zener diode. The Zener withstands a higher cut-off voltage and switches off faster, at the cost of a longer cut-off delay than an unprotected circuit.

For AC coils, fit a varistor or an RC element. The varistor limits the amplitude of the cut-off current but does not reduce its steepness. The RC element reduces both.

Unsuppressed contactor coils are one of the most common causes of output module failure. If the replacement goes back into the same circuit, expect the same result.

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 an output module for a distributed rack rather than a central one, everything on this page applies.

Front connectors

Every SM 322 ships without one.

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 6ES7322-1BP00-0AA0 and 6ES7322-1BP50-0AA0 use two 40-pin blocks each.

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