GE HE693THM809C Series 90-30 Thermocouple Input Module

The General Electric HE693THM809C, also cataloged as the HE693THM809 Thermocouple Input Module, operates as a dedicated hardware component for temperature sensor signal processing within GE Series 90-30 PLC backplane platforms. The module accepts direct millivolt analog inputs generated by field thermocouple sensors across 8 differential channels, digitizes the signals via onboard 16-bit Sigma-Delta analog-to-digital converters, and streams linearized temperature telemetry across the 48-pin rack backplane interface to the CPU.

Hardware Specifications

Backplane Bus Communication Velocity & I/O Density Scaling

The HE693THM809C incorporates an onboard microcontroller and dual memory chips to maintain deterministic data update schedules across the Series 90-30 backplane bus. The module executes internal cold junction compensation (CJC) via dual onboard temperature sensors while maintaining 120 dB common mode rejection to isolate low-level millivolt signals from backplane communication noise. Onboard signal conditioning circuits and EMI filter stages ensure high-density analog scaling without incurring data transmission latencies or CPU scan time degradation during continuous bus arbitration.

Frequently Asked Questions

Q: Is hot-swapping permitted for the HE693THM809C module during active rack operation?

A: No. Backplane power to the Series 90-30 rack baseplate must be completely de-energized prior to inserting or removing the HE693THM809C module to avoid transient voltage spikes on the 48-pin backplane connector.

Q: What is the maximum continuous overvoltage limit supported on the input terminals?

A: The differential input channels incorporate protection diodes and signal conditioning circuitry designed to withstand a maximum continuous input voltage of ±30 VDC.

Q: How is cold junction compensation handled across the thermocouple input channels?

A: Cold junction compensation is executed automatically per channel using two integrated onboard temperature sensors that feed reference thermal data to the 16-bit Sigma-Delta ADC pipeline.

Field Installation Guidelines

Ensure main power to the Series 90-30 baseplate frame is de-energized prior to module installation. Align the 48-pin rear male connector with the backplane slot guide rails and push the module firmly until the top and bottom mounting clips seat into the rack frame. Secure field wiring directly to the 20-pin removable screw terminal block using twisted-pair shielded thermocouple extension wire. Connect signal cable shields to a single, dedicated low-impedance ground point on the panel baseplate to prevent ground loops and maintain noise suppression limits.