The VT 400 is a panel-mount digital weight indicator and batch controller from VPG Transducers — the sensors division of Vishay Precision Group, whose foil strain gauge technology is the industry reference for load cell sensing elements worldwide. Designed for industrial process weighing rather than simple check-weighing, the VT 400 combines legal-for-trade metrology (OIML R-76 Class III/IIIL, EU Type Approval DK0199.62) with the speed and connectivity required for automated batching, filling, and inventory management. It excites and reads up to ten 350-ohm load cells with 6-wire sensing — compensating for cable resistance changes with temperature — at a selectable conversion rate from 3 to 228 samples per second.

How does the VT 400 serve batch control applications?

Two programmable logic outputs (24V DC, opto-isolated to 2.5 kV) function as weight setpoints for simple two-speed filling control: a fast-fill relay opens at coarse weight, a dribble-feed relay closes at target, and the controller automatically tares before the next cycle. The single logic input (9–24V DC, opto-isolated) accepts an external start command or gross/net toggle. For more complex multi-component batching, up to 30 VT 400 units can be networked on a single RS485 bus, with a PLC or PC coordinating the sequence. The optional 16-bit analog output (4–20 mA or 0–10 V, 0.01% linearity) transmits the live weight signal to a PLC analog input card for PID-controlled dosing or extruder throughput regulation.

What data integrity features does the VT 400 provide?

The built-in alibi memory stores the last 10,000 weigh transactions in non-volatile flash — timestamped, unalterable, and retrievable via RS232 — providing the audit trail required for pharmaceutical batch records, food ingredient traceability, and legal-for-trade custody transfer. The FIR digital filter (automatically adjusted to the selected conversion speed) plus a post-filter rolling average (1, 2, 4, 8, 16, or 32 samples) provides configurable noise rejection for weigh vessels on vibrating machinery. Auto-zero tracking and a full-scale (100%) taring range ensure stable net-weight readings even as residual product accumulates in the weigh hopper over successive batches.