How to Select an Interface Relay for PLC Outputs
A step-by-step guide to matching PLC output type, coil voltage and current, contact rating, and socket style when selecting an interface relay.
The Schneider Electric SR2B121JD is a Zelio Logic SR2 compact smart relay with 8 discrete inputs (4 configurable as analogue) and 4 relay outputs rated 8 A each, powered from 12 V DC. Its built-in LCD display and navigation buttons, with a real-time clock, let you program, monitor, and diagnose simple automation tasks directly on the unit.
The SR2B121JD is the 12 V DC member of the 12-I/O Zelio Logic SR2 compact range, with a built-in real-time clock for time-based control such as scheduled lighting or pump cycling and 4 of its inputs configurable as 0-10 V analogue channels for simple threshold or setpoint monitoring. Where fewer or more I/O points are needed, the 10-I/O and 20-I/O SR2 variants in the same family cover the range without changing the programming environment.
| Range of Product | Zelio Logic |
|---|---|
| Product or Component Type | Compact smart relay |
| Local display | With |
|---|---|
| Number or control scheme lines | 0…240 ladder, 0…500 FBD |
| Cycle time | 6…90 ms |
| Backup time | 10 years 77 °F (25 °C) |
| Clock drift | 12 min/year 32…131 °F (0…55 °C), 6 s/month 77 °F (25 °C) |
| Checks | Program memory on each power up |
| [Us] rated supply voltage | 12 V DC |
| Supply voltage limits | 10.4…14.4 V |
| Maximum supply current | 120 mA without extension) |
| Power dissipation in W | 1.5 W without extension |
| Reverse polarity protection | With |
| Discrete input number | 8 IEC 61131-2 Type 1 |
| Discrete input type | Resistive |
| Discrete input voltage | 12 V DC |
| Discrete input current | 4 mA |
| Counting frequency | 1 kHz discrete input |
| Voltage state 1 guaranteed | >= 7 V IB...IG used as discrete input circuit, >= 5.6 V I1...IA and IH...IR discrete input circuit |
| Voltage state 0 guaranteed | <= 3 V IB...IG used as discrete input circuit, <= 2.4 V I1...IA and IH...IR discrete input circuit |
| Current state 1 guaranteed | >= 2 mA I1...IA and IH...IR discrete input circuit), >= 0.5 mA IB...IG used as discrete input circuit) |
| Current state 0 guaranteed | <= 0.2 mA IB...IG used as discrete input circuit), <= 0.9 mA I1...IA and IH...IR discrete input circuit) |
| Input compatibility | 3-wire proximity sensors PNP discrete input |
| Analogue input number | 4 |
| Analogue Input Type | Common mode |
| Analogue input range | 0...10 V, 0...12 V |
| Maximum permissible voltage | 14.4 V analogue input circuit |
| Analogue input resolution | 8 bits at maximum voltage |
| LSB value | 39 mV analogue input circuit |
| Conversion time | Smart relay cycle time analogue input circuit |
| Conversion error | +/- 5 % 77 °F (25 °C) analogue input circuit, +/- 6.2 % 131 °F (55 °C) analogue input circuit |
| Repeat accuracy | +/- 2 % 131 °F (55 °C) analogue input circuit |
| Operating distance | 10 m between stations, with screened cable (sensor not isolated) analogue input circuit |
| Input impedance | 14 kOhm IB...IG used as analogue input circuit, 14 kOhm IB...IG used as discrete input circuit, 2.7 kOhm I1...IA and IH...IR discrete input circuit |
| Number of Outputs | 4 relay |
| Output voltage limits | 24...250 V AC relay output), 5...30 V DC relay output) |
| Contacts type and composition | NO relay output |
| Output thermal current | 8 A for all 4 outputs relay output |
| Electrical durability | AC-12 500000 cycles 230 V, 1.5 A relay output IEC 60947-5-1, AC-15 500000 cycles 230 V, 0.9 A relay output IEC 60947-5-1, DC-12 500000 cycles 24 V, 1.5 A relay output IEC 60947-5-1, DC-13 500000 cycles 24 V, 0.6 A relay output IEC 60947-5-1 |
| Switching capacity in mA | >= 10 mA 12 V relay output) |
| Operating rate in Hz | 0.1 Hz at Ie)relay output, 10 Hz no load)relay output |
| Mechanical durability | 10000000 cycles relay output |
| [Uimp] rated impulse withstand voltage | 4 kV EN/IEC 60947-1 and EN/IEC 60664-1 |
| Clock | With |
| Response time | 10 ms from state 0 to state 1)relay output, 5 ms from state 1 to state 0)relay output |
| Connections - terminals | Screw terminals, 1 x 0.2...1 x 2.5 mm² 25 AWG...14 AWG) semi-solid, Screw terminals, 1 x 0.2...1 x 2.5 mm² 25 AWG...14 AWG) solid, Screw terminals, 1 x 0.25...1 x 2.5 mm² 24 AWG...14 AWG) flexible with cable end, Screw terminals, 2 x 0.2...2 x 1.5 mm² 24 AWG...16 AWG) solid, Screw terminals, 2 x 0.25...2 x 0.75 mm² 24 AWG...18 AWG) flexible with cable end |
| Tightening torque | 4.4 lbf.in (0.5 N.m) |
| Overvoltage category | III conforming to IEC 60664-1 |
| Net Weight | 0.55 lb(US) (0.25 kg) |
| Immunity to microbreaks | 1 ms repeated 20 times |
|---|---|
| Product Certifications | C-tick, UL, CSA, GOST, GL |
| Standards | IEC 61000-4-11, IEC 60068-2-6 Fc, IEC 61000-4-12, IEC 61000-4-2 level 3, IEC 61000-4-5, IEC 61000-4-3, IEC 61000-4-4 level 3, IEC 60068-2-27 Ea, IEC 61000-4-6 level 3 |
| IP degree of protection | IP20 IEC 60529 terminal block), IP40 IEC 60529 front panel) |
| Environmental characteristic | EMC directive conforming to IEC 61000-6-2, EMC directive conforming to IEC 61000-6-3, EMC directive conforming to IEC 61000-6-4, EMC directive conforming to IEC 61131-2 zone B, Low voltage directive conforming to IEC 61131-2 |
| Disturbance radiated/conducted | Class B EN 55022-11 group 1 |
| Pollution degree | 2 IEC 61131-2 |
| Ambient air temperature for operation | -4…104 °F (-20…40 °C) in non-ventilated enclosure IEC 60068-2-1 and IEC 60068-2-2, -4…131 °F (-20…55 °C) IEC 60068-2-1 and IEC 60068-2-2 |
| Ambient Air Temperature for Storage | -40…158 °F (-40…70 °C) |
| Operating altitude | 6561.68 ft (2000 m) |
| Maximum altitude transport | 10000 ft (3048 m) |
| Relative Humidity | 95 % without condensation or dripping water |
| Part number | SR2B121JD |
|---|---|
| Brand | Schneider Electric |
| Condition | New, factory sealed |
| Source | Schneider Electric and its authorised distributors |
| Warranty | Manufacturer warranty |
| Lifecycle status | Active, in production |
| EAN | 3389110549171 |
| Warranty (in months) | 18 |
|---|
| Country of origin | FR |
|---|---|
| Shipping weight | 0.25 kg |
| Ships from | Türkiye |
| Dispatch | — |
| Stock | On request |
Source: manufacturer data · Last verified: 30 Oct 2026
No documents are on file for this part yet.
Ask us for the datasheetThe tariff (HS) code on file for SR2B121JD is 853710.
The EAN (GTIN) of SR2B121JD is 3389110549171.
SR2B121JD ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival.
A step-by-step guide to matching PLC output type, coil voltage and current, contact rating, and socket style when selecting an interface relay.
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