MTL 5511 Digital Isolator | 2-Ch DI/DO, 4-20mA Output, IS, DIN Rail, ATEX/IECEx/FM Specs

MTL 5511 Digital Isolator | 2-Ch DI/DO, 4-20mA Output, IS, DIN Rail, ATEX/IECEx/FM Specs

MTL 5511 dual-channel digital isolator specifications. Two 24V DC digital inputs/outputs, isolated 4-20mA outputs, programmable, 24V DC, DIN rail. ATEX/IECEx/FM certified.

Product Overview

The MTL 5511​ is a dual-channel, programmable isolator​ from MTL's 5500 series, designed to convert digital signals (24V DC switch/relay contacts or transistor outputs) into isolated analog signals (4-20mA). Each channel can be individually configured as a digital input (DI) or a digital output (DO). In DI mode, it senses a contact closure or transistor signal from the hazardous area. In DO mode, it acts as a contact closure driven by a safe-area 4-20mA signal. It provides intrinsic safety (IS) isolation​ and is ideal for interfacing digital field devices with analog control systems.

Technical Specifications

Note: Specifications are based on MTL 5500 series documentation. The 5511 is software-configurable. Always verify with the latest product datasheet.

Key Features

• Dual-Channel Flexibility:​ Each channel can be independently configured as a Digital Input (DI)​ or Digital Output (DO), offering application flexibility.

• Digital to Analog Conversion:​ Converts dry contacts or 24V signals into a precise 4-20mA signal for analog control systems.

• Analog to Digital Conversion:​ Converts a 4-20mA control signal into a hazardous-area contact closure (relay) for actuating valves, alarms, etc.

• Fully Programmable:​ Software configuration allows setting precise trip points, hysteresis, and fail-safe modes for each channel.

• Intrinsic Safety:​ Certified for Zone 1/21, allowing direct connection to field devices in hazardous areas.

• Complete Isolation:​ 500V isolation between channels and between field and safe areas.

• Compact & High-Density:​ Only 12.5mm wide, saving valuable panel space.

• Visual Diagnostics:​ Per-channel bicolor LEDs indicate status (On, Off, Fault).

• Global Hazardous Area Approvals:​ Suitable for worldwide installations.

Operating Modes

Mode 1: Digital Input (DI) to 4-20mA Output

• Application:​ Monitoring a switch (e.g., level switch, pressure switch, limit switch) or a proximity sensor in a hazardous area.

• Function:​ The 5511 senses the state of the switch/contact. It outputs a programmable 4-20mA value for the "On" state (contact closed) and a different programmable value for the "Off" state (contact open). (e.g., 4mA=Off, 20mA=On, or vice versa).

Mode 2: Digital Output (DO) from 4-20mA Input

• Application:​ Actuating a device (e.g., solenoid valve, alarm horn, relay) in a hazardous area based on an analog control signal.

• Function:​ The 5511 monitors a 4-20mA input signal. When the signal crosses a user-programmable threshold, its internal solid-state relay energizes, closing the circuit to the field device.

Wiring & Configuration Examples

Example 1: Digital Input (DI) Mode - Monitoring a Limit Switch

[Hazardous Area]        [MTL 5511 Ch1]        [Safe Area]
Limit Switch ----+---- Terminal 1 (DI+)   Terminal 3 (AOut+) ----[+24V Out PSU]
                 |                        Terminal 4 (AOut-) ----[PLC AI Card]
[IS 24V +] ------+---- Terminal 2 (DI-)

Software config: Set Ch1 as DI. Set "On" current=20mA, "Off" current=4mA.

Example 2: Digital Output (DO) Mode - Driving a Solenoid Valve

[Safe Area]             [MTL 5511 Ch2]        [Hazardous Area]
[PLC AO Card] ---- Terminal 4 (AIn-)   Terminal 2 (DO-) ---- Solenoid Valve ----+
                     Terminal 3 (AIn+)   Terminal 1 (DO+) ----[IS 24V +]---------+

Software config: Set Ch2 as DO. Set trip threshold=12mA (energize valve at >12mA).

Entity Parameters (for Hazardous Area Loop Design) - Per Channel

Note: The connected field device (switch, solenoid) in the hazardous area must be IS certified or a Simple Apparatus.

Configuration Software

The MTL 5511 is configured using the MTL Software Suite​ (or similar) and a USB programming cable. Configuration parameters include:

• Channel Mode:​ Digital Input (DI) or Digital Output (DO).

• Trip Points (DI Mode):​ Set the exact 4-20mA output value for the "On" and "Off" states.

• Trip Points (DO Mode):​ Set the mA threshold and hysteresis for energizing the output.

• Fail-Safe Mode:​ Define output state on power loss or fault.

• Response Time:​ Filter/debounce settings.

Typical Applications

• Level Switch Monitoring:​ Convert the signal from a high/low-level switch in a tank to a 4-20mA signal for the DCS.

• Valve Position Feedback:​ Convert limit switch signals from an actuator to an analog feedback signal.

• Alarm Annunciation:​ Convert a hazardous area alarm contact (e.g., gas detector alarm) to a proportional signal for the control room.

• Solenoid Valve Control:​ Convert a 4-20mA control signal to a dry contact output to energize a solenoid valve in a hazardous area.

• Motor Start/Stop Status:​ Interface motor contactor auxiliary contacts to an analog input card.

• Interlock Signals:​ Isolate and convert digital interlock signals between hazardous and safe areas.

Important Technical Notes

1. Software Configuration Required:​ Unlike DIP-switch models, the MTL 5511 requires a PC and configuration software to set up.​ It is not functional out of the box without programming.

2. Power Supplies:​ Requires separate power supplies: 24V DC for module electronics​ and, in DI mode, an IS 24V supply​ to power the field switch circuit. In DO mode, the 5511 acts as a switch, powered by the IS supply connected to the field device.

3. Dry Contact vs. Active Input:​ In DI mode, it can accept a dry contact (switch) or an active 24V DC signal. Ensure the configuration matches the field device.

4. Output is Solid-State:​ The DO is a solid-state switch, not a mechanical relay. Ensure it is suitable for the load (inductive, lamp, etc.).

5. Analog Output in DI Mode:​ The 4-20mA output in DI mode is an active, sourcing output​ and requires an external 24V DC power supply to form the loop.

6. Analog Input in DO Mode:​ The 4-20mA input in DO mode is a passive, sinking input. It must be driven by an active source (e.g., a PLC analog output card).

7. LED Indicators:​ Clearly show the state of each channel's digital circuit (field side).

8. SIL Considerations:​ For Safety Instrumented Systems (SIL 2), follow all manufacturer guidelines for configuration and proof testing.

Note: This data sheet provides general specifications for the MTL 5511 digital/analog isolator. For complete installation instructions, wiring diagrams, software configuration guide, intrinsic safety guidelines, and certification details, consult the official MTL 5500 Series Technical Manual​ and the product-specific data sheet. Programming software and cable are required for setup.