Model Interpretation

9905: MicroNet Plus series auxiliary I/O module general code;

973: Specification code for 8 independent isolated relay output channel, DIN rail/rack plug-in installation, standard industrial cabinet version。

Technical Specifications

Electrical Parameters

Power Supply: 24VDC from backplane rack bus, rated working current ≤0.8A

Operating Temperature: 0℃ ~ +60℃; Storage Temp: -20℃ ~ +80℃, RH 5%~95% non-condensing

Outline Size: 155×98×32mm, Net Weight ≈0.48kg, standard 3U rack card structure

Certification: CE, UL industrial safety certification, PCB conformal coating for anti-corrosion in damp oily cabinet environment

Channel Specification

Total 8 independent relay output channels, each channel isolated dry contact (SPDT single-pole double-throw);

Single contact rated load: AC250V/5A, DC30V/5A, no common channel power bus;

Each channel with onboard status indicator LED for contact pull-in/open state display.

Interface and Communication Configuration

Front side: 8-channel independent status indicator LED for real-time on-site channel state check;

Rear edge connector: Gold-plated backplane plug for rack bus communication and power take-in, no external hard wiring for internal bus;

Terminal side: Screw terminal block for field equipment wiring of each relay channel;

Bus Protocol: Internal MicroNet proprietary rack bus, data interaction with main CPU module via backplane, no external independent communication port。

Core Functions

Receive digital switch command from MicroNet main CPU, drive corresponding channel relay contact pull/open to realize field equipment on-off control.

Independent channel isolation design, single-channel short-circuit or overload will not interfere other 7 channels and rack main control bus.

Real-time channel status feedback via onboard LED, convenient for on-site fault location and maintenance inspection.

Built-in overcurrent protection on each output loop, prevent field wiring short-circuit damage to internal module circuit and rack CPU.

Hot-swappable within power-off rack slot, replace spare module without whole control cabinet power cut。

Applicable Scenarios

Gas turbine/steam turbine emergency trip interlock circuit, auxiliary oil pump, drain valve, cooling fan logic control in petrochemical captive power plant, waste heat power station, blast furnace gas power generation unit MicroNet control cabinet。

Operation and Maintenance Guidelines

Keep cabinet internal dry, away from oil mist, dust and corrosive gas, avoid installation beside inverter and high-power contactor with strong electromagnetic interference.

Periodically tighten field wiring screw terminals to prevent poor contact causing contact burnout and control failure.

Replace with original 9905-973 spare module only; no parameter configuration needed after replacement, module automatically identifies rack bus address after power on.

Abnormal channel: firstly check field load short-circuit or overload, confirm external circuit normal before judging internal relay damage of module.