SISO vs. MIMO in Automated SMT Reel Storage: Which Operating Mode Fits Your Line?
Automated reel storage systems work in one of two operating modes. In single-in single-out (SISO) mode the system handles one reel per operation. In multi-in multi-out (MIMO) mode it stores and retrieves several reels in parallel. Neither is better in general: the right mode depends on how many reels move per shift, how many lines are kitted at the same time and how much operator time you can spend at the storage port. This guide explains the difference and what to measure before you decide.
What the two modes mean
- SISO: a reel is presented at the port, identified, positioned and stored, then the port is free for the next one. Retrieval follows the work order reel by reel, normally with FIFO enforced.
- MIMO: several reels are loaded or output in one operation. Work orders are dispatched as a batch.
What differs in daily operation
| Situation | SISO | MIMO |
|---|---|---|
| Goods-in: a delivery of many reels | Reels go in one after another; someone (or a robot) feeds the port until the batch is done | The batch is loaded in a few operations and the operator moves on |
| Kitting one work order | Reels come out in sequence, one at a time | Several reels come out in parallel; whole work orders are dispatched as a batch |
| Several lines changing over at once | Requests queue at the single port | Parallel output serves several lines at once |
| Footprint and investment | Smallest footprint, entry-level investment | Larger system, higher throughput |
What to measure before choosing
- Reel movements per shift, in and out, and the peak hour.
- How many lines are kitted at the same time during a changeover.
- Operator minutes spent at the storage port per shift today.
- Kitting lead time for one of your real work orders, from request to reels on the trolley.
- Reels per incoming delivery at goods-in.
- Your growth plan: lines and part numbers in two to three years.
Rules of thumb
SISO suits small-batch production with one or two lines and moderate daily reel movements: the port is rarely the bottleneck, and the smaller system costs less and takes less floor space. MIMO pays off when three or more lines are kitted at the same time, when changeovers are frequent, or when goods-in arrives in large batches, because the time an operator spends feeding the port grows with every reel in SISO mode. Plants in between can combine modes, for example a high-throughput central store with smaller near-line units.
How Neotel implements the two modes
- SMD BOX SISO: one reel per operation, 1,000-reel capacity for 7–15 inch reels, FIFO retrieval by work order, AGV integration, the smallest footprint in the SMD BOX family.
- SMD BOX MIMO: multi-reel parallel input and output, batch work-order dispatch and AGV integration, intended for high-frequency retrieval with three or more production lines.
- SMD BOX DUO: dual modules with MIMO capability for balanced throughput.
All models run on the SMF material-flow software. Compare them on the SMD BOX series page, or send us your reel movements per shift and number of lines and we will suggest a configuration: request a quote.
Frequently asked questions
- What does SISO mean in SMT reel storage?
- Single-in single-out: the storage system stores or retrieves one reel per operation. It is the simplest and most compact form of automated reel storage.
- What does MIMO mean in SMT reel storage?
- Multi-in multi-out: the system stores and retrieves several reels in parallel and dispatches whole work orders as a batch, which raises throughput when several lines are supplied at once.
- When is SISO enough?
- When one or two lines are supplied, daily reel movements are moderate and the storage port is not a bottleneck during changeovers. Measure operator minutes at the port and kitting lead time to confirm.
