Digital inputs

Digital inputs are designed to detect binary logic states (TRUE/FALSE) and can also function as counters for applications like reading pulse data from meters or monitoring engine RPM. Additionally, the DirectSwitch function enables direct input-to-output connections for time-sensitive operations.

Indicating Logic States

• TRUE State - When active (voltage between 7-35 V⎓), an LED corresponding to the input label lights up

• FALSE State - Voltage below 3 V⎓ indicates a FALSE state

• Non-Defined State - Voltage between 3-7 V⎓ is considered undefined

Connection

• Each digital input connector has a common DIGND terminal for connecting the negative pole of the DC power supply

• The positive pole of the power supply is connected to the DI terminal (e.g., DIx or DIy.x) via the external device

To maintain galvanic isolation, use a separate power supply for external devices connected to digital inputs.

Special functions

Debounce

• Filters out signal noise by requiring a signal to maintain a TRUE state for a specified duration before being processed.

• Configurable in increments of 100 µs (e.g., a value of 10 equals 1 ms).

Counter Input

• High-speed counters register rising edges independently of the control software.

• Suitable for recording data from energy, water, or gas meters, as well as engine RPMs.

• Features 64-bit registers, resetting to 0 after exceeding 4,294,967,295 counts.

• Operates at frequencies up to 10 kHz, labeled as CNT inputs in Mervis IDE.

DirectSwitch

• Allows direct mapping of digital inputs to digital or relay outputs for time-critical applications.

• Modes:

  • Copy: Output mirrors the input state.

  • Inverse Copy: Output is the negation of the input state.

  • Switch: Toggles the output state on an input's rising edge.

  • Block: Disables DirectSwitch.

• Only corresponding inputs and outputs (e.g., DIx.y and DOx.y) can be linked. Multiple outputs cannot share a single input.

• When in use, outputs cannot be controlled conventionally without setting the ForceOutput register to TRUE for 1 second.

Default Configuration

Stores section settings for reloading after a power cycle or reboot:

• Debounce - 5 ms

• DirectSwitch - Disabled

• Counter - Resets to 0

Master Watchdog

Ensures safe fallback configurations by monitoring application commands. If commands are absent within a set timeout, the module reboots and reverts to default settings, minimizing risks during software or hardware failures.

Technical Specifications

Parameter	Value
Input Type	SINK
Input Terminal	DI
Common Ground	DIGND
Maximum Voltage for FALSE	3 V⎓
Minimum Voltage for TRUE	7 V⎓
Maximum Voltage	35 V⎓
Non-Defined Voltage Range	3-7 V⎓
Input Resistance (TRUE State)	6,200 Ω
Voltage Drop on DI Diode	1.2 V
Minimum Pulse Length	20 µs
FALSE → TRUE Delay	20 µs
TRUE → FALSE Delay	60 µs
Maximum CNT Frequency	10 kHz
Galvanic Isolation (Between Groups)	Yes
Insulation Voltage	2,000 V