In an automated brewery control system, the control panel acts like the system’s brain and nervous system. It collects signals from sensors in the field, makes decisions based on those signals, and sends commands to start or stop equipment.
So Which PLC Brain Fits Your Brewery Line-S7-1200 or S7-1500?
Choosing the right controller model(for example, Siemens S7-1200 or S7-1500) based on your actual system setup, is critical for keeping your beer production efficient and stable.
In small brewery systems, for example like between 500L and 1000L, the Siemens S7-1200 is often chosen as the PLC control cabinet. This model supports up to 8 signal expansion modules, with approximately 1024 digital input/output points and about 256 analog input/output points.
So what are digital and analog signals precisely?
Digital Signals: represent only two states: on or off, open or closed, 1 or 0.
For example, a level switch telling the PLC “the tank is full” or a start button sending a “push” signal, these are simple yes/no signals.
Analog Signals: represent a continuous range of values, such as temperature, pressure, or liquid level. For example, a temperature sensor telling the PLC “the mash is exactly 67.5℃ or a pressure transmitter reporting 2.3 bar, these signals vary smoothly instead of being just on or off.
In short, digital signals answer yes/no questions, while analog signals answer “how much?”
Examples of Valve Signal Types in a Brewery Control System
In an automated brewery control system, different types of valves require different signal configurations. Here are common examples:
| Valve Type | Typical Signal Configuration | Explanation |
| Solenoid valve | 1 DO | Only two states: open or closed. The PLC sends a DO signal (energize/de-energize) to switch the valve. Example: water or steam valves in CIP lines. |
| Pneumatic butterfly valve | 1 DO + 1 DI | DO controls the valve to open/close (via a solenoid pilot). DI provides feedback (open/closed position).
Example: material inlet/outlet valves on a mash tun. |
Simple rule:
DO only: you can command open/close, but you don’t know if it actually moved (not recommended alone)
DO + DI: you can command and verify the action (recommended)
AO + AI: continuous modulation, like turning a volume knob
How many valves in a typical small brewery system (500L–1000L, brewhouse + fermentation)?
Take a typical craft brewery system (brewhouse unit + 4 fermenters + CIP) as an example:
| Area | Valve Type | Approx. Quantity | Signal Type per Valve |
| Brewhouse | Solenoid valves (water, steam, CIP) | 4–6 | 1 DO each |
| Pneumatic butterfly valves | 6–10 | 1 DO + 1 DI each | |
| Pump | 1–2 | 1DI + 1DO+1AO each | |
| Fermentation (per tank) | Pneumatic butterfly valves (in/out, vent, sample) | 4–5 per tank | 1 DO + 1 DI each |
| Solenoid valves (CO2, CIP return) | 1–2 per tank | 1 DO each | |
| CIP unit | Solenoid valves (acid/alkali/water distribution) | 4–6 | 1 DO each |
| Pneumatic butterfly valves (return pump outlet, etc.) | 2–4 | 1 DO + 1 DI each |
Rough total (brewhouse+ 4 fermenters + CIP):
Total number of valves: approximately 30–50
On/off type valves (DO or DO+DI): about 25–40
Modulating type valves (AO+AI): about 1–3
This is why the S7-1200 is sufficient for small systems. It supports up to 1024 digital points – even 50 valves (each using 1–2 DI/DO) is well within the limit. Analog points are mainly used for temperature, pressure, and level sensors, typically not exceeding 30 points.
When a brewery system scales up to 2000L or more, (e.g., 2000L, 5000L, or even 10,000L) brewhouse systems with 10, 20 or more fermenters, control requirements change significantly. In such cases, the Siemens S7-1500 or higher series becomes the more suitable choice.
Estimated Totals:
DI/DO: approximately 300-600 points
AI/AO: approximately 100-200 points
When your brewery system reaches 2000L or more, with dozens of fermenters, hundreds of valves, and many sensors–the S7-1500 not only meets the requirements but also significantly improves production efficiency, reduces labor costs, and ensures consistent product quality through its advanced control capabilities.
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