The Trusted TMR 24V dc digital input module interfaces to 40 field input devices. A wide input voltage range and programmable thresholds allow the module to be used in current source and current sink configurations. Comprehensive diagnostic tests are performed on each input channel, including tests for stuck on and stuck off failures. Fault tolerance is achieved through Triple Modular Redundancy (TMR) within the same module for each of the 40 input channels.
When a line-monitoring device is installed at the field switch, the module can detect open and shorted field cables. Line monitoring can be independently configured for each input channel.

The module provides on-board sequence of events (SOE) reporting with a resolution of 1ms. A change of state triggers an SOE entry. States are determined by programmable voltage thresholds that can be configured on a per channel basis. When the field voltage and field return are connected to the auxiliary input channels of the module, thresholds can be specified as a ratio of the current field supply voltage.

Each triplicated section of the module, referred to as a slice, conditions and measures each channel independently. Each slice is optically isolated up to 2500V dc. Each slice sends its data to a safety layer hardware voter that presents the information from all three slices to the Trusted TMR processor. When a fault is detected on a slice of the module, the Trusted TMR processor will flag the error, indicating the need to replace the module. The Trusted TMR processor will continue to use the information provided by the remaining two slices until a replacement module is available. Replacement modules can be located in a standby slot next to the module or in a designated SmartSlot with a temporary connection to the same Trusted termination assembly.

Modules may be placed in any I/O module slot in a Trusted processor chassis or expander chassis. Once the I/O module configuration is set, mechanical keying is available on all I/O modules to prevent inserting a module into an incorrect slot.

Configuration of the module is carried out using the Trusted Toolset running on an engineering workstation. Once configured and loaded into the Trusted controller, replacement modules are online educated by the TMR processor.

Features
40 TMR input channels per module.
Comprehensive diagnostics and self-test.
Line monitoring on a per channel basis.
2500V dc optically isolation.
On-board 1ms resolution sequence of events reporting.
Hot replaceable.
Front panel status LEDs for each channel.
Module fault and status indicators.
IEC 61508, SIL 3 safety applications.