MVI56-S3964R PROSOFT

Model: MVI56-S3964R
Brand: ProSoft Technology
Series: MVI56 (ControlLogix in-chassis)
Core Function: Siemens 3964R point-to-point serial protocol bridge
Type: Siemens 3964R Network Interface Module
Key Specs: 2 RS232/422 ports, 512 bytes max transfer, 800 mA @ 5.1 Vdc

Product Introduction

Field observation: you’ll see MVI56-S3964R show up in brownfield upgrades where a ControlLogix rack needs to talk Siemens 3964R to legacy S5/S7 point-to-point partners, usually drives or RTUs that nobody wants to replace. The module takes a single 1756 slot and gives you two independent RS-232/422 serial ports running the full 3964R protocol (RK512 mode included), with ladder logic handling the data movement between the module’s database and processor tags.

Siemens designed 3964R for reliable bi-directional point-to-point transfers with BCC checksums, and this ProSoft implementation supports DB-SEND/DB-FETCH in RK512 mode plus basic read/write in standard mode, up to 512 bytes per transaction. Backplane load hits 800 mA at 5.1 Vdc with a 0–60 °C operating band, so rack power and cabinet thermal checks are non-optional, especially in remote rack scenarios.

Key Selling Points & Differentiators

Dual independent serial ports let one ControlLogix CPU maintain two separate 3964R links to different Siemens partners, with ports running RS-232/422/485 and full hardware handshaking for radio/modem/drop applications.
RK512 mode support gives you header evaluation (DB/DW bytes 9-10) for advanced Siemens coordination, while standard 3964R handles basic block transfers—all with configurable byte swapping for word format matching.
Maximum 512-byte transfers cover most practical Siemens point-to-point needs without fragmenting data across multiple telegrams, keeping ladder logic straightforward.
Compared to custom serial drivers or external converters, the dedicated 3964R implementation handles BCC checksums, timeouts, and protocol specifics natively, reducing ladder complexity and field debug time.
Not recommended for new Ethernet-native Siemens gear; if the partner supports S7/TCP or Profinet, align on those instead and reserve MVI56-S3964R for unavoidable legacy serial 3964R links.
Stock spares should carry a test report proving power-on, 3964R transfers on both ports (RK512 where applicable), and 24+ hour burn-in; without documented protocol exercise, treat as unverified hardware.