Connecting hydraulic-cylinder position switches to an injection molding machine may appear to be a simple wiring task. However, the type of switch and the electrical architecture of the machine must be considered before choosing how the sensors should be connected.
A Vega technical case illustrates this clearly. A Customer asked whether several Vega switches, originally configured with multiple wires, could be connected to a machine using only two wires. The Vega Team reviewed the different switch technologies and identified which switches could be used and which needed to be replaced.
The case is particularly useful because it shows that not all three- or four-wire sensors can simply be connected to a two-wire machine.
Two-wire and three-wire systems are not automatically interchangeable
The first question to answer when replacing or connecting a cylinder switch is not simply how many wires are physically present.
The important question is:
What type of electrical output does the switch provide, and what type of input does the machine expect?
In the technical exchange, the Customer specifically asked whether the MSU1, MSU2, MSU3 and MSU4 switches could be connected to a machine designed for two-wire connections. The same question was raised for switches used on V450 and V260 cylinders.
The Vega Team’s answer differentiated between the various switch technologies rather than treating all switches in the same way.
This distinction is essential when troubleshooting an existing mold.
MSU1 and MSU4: a direct two-wire connection is not possible
For the MSU1 and MSU4, the Vega Team stated that they could not be connected to the machine using only two wires.
The recommended solution was therefore to replace them with suitable alternative switches.
The current Vega product range confirms that the MSU1 is a magnetic switch for the V215CR hydraulic cylinder, while the MSU4 is a magnetic switch for the V220CC.
MSU1 Magnetic Switch – Vega Cylinders — Official Vega product page for the MSU1 magnetic switch used with the V215CR.
MSU4 Magnetic Switch – Vega Cylinders — Official Vega product page for the MSU4 magnetic switch used with the V220CC.
Recommended alternatives for the different switch configurations
The technical response provided specific replacement paths:
- MSU1 → MSRC / MSRB
- MSU2 / MSU3 → MSRI
- MSU4 → Type “Y”, order code ZD030422A
This is an important point when working with legacy installations.
The correct replacement cannot be selected simply according to the physical shape of the switch. The electrical interface with the machine must also be considered.
For this reason, the technical documentation and the cylinder configuration should be checked before ordering a replacement switch.
Why the switch type matters
Vega’s current product range includes several different technologies for hydraulic-cylinder end-position detection, including:
- magnetic switches;
- inductive switches;
- mechanical switches.
The official Vega website groups these products under Hydraulic Cylinder End-Stroke Switches.
Hydraulic Cylinder End-Stroke Switches – Vega Cylinders — Official Vega overview of magnetic, inductive and mechanical switches for hydraulic cylinders.
This variety exists because the switch must be compatible not only with the machine’s electrical system, but also with the construction of the hydraulic cylinder itself.
Three wires do not always mean that three wires must be connected
The situation is different for the mechanical switches used on CM cylinders and the MSK switch used on V260 cylinders.
The Vega Team explained that these switches have three wires, but only two are required for connection to the machine:
- common C;
- normally open contact NO.
The third wire does not have to be used in this configuration.
This is an important distinction.
A switch having three wires does not automatically mean that the machine needs a three-wire input. A mechanical contact can have multiple available terminals, while the machine may use only the common and normally open contacts.
The correct wiring therefore depends on the electrical function of each conductor, not simply on the number of wires coming from the switch.
Mechanical switches and electronic sensors are different
This distinction becomes even more important when comparing mechanical switches with electronic sensors.
A mechanical switch works as an electrical contact. The machine can therefore use the contact between the common and normally open terminals as a simple ON/OFF signal.
An electronic inductive or magnetic sensor may instead require a power supply and provide an electronic output.
This is why the Vega Team did not recommend treating all three-wire switches as if they were equivalent.
Vega’s current product range reflects this distinction by listing mechanical, magnetic and inductive switches as separate product categories.
The V260 example: MSJ versus MSK
The case also provides an especially useful example concerning the V260 cylinder.
The Customer asked whether the three-wire switches used on the V260 could be connected to a two-wire machine.
The Vega Team explained that the MSJ inductive switches have three wires and cannot be connected using only two wires.
For this type of cylinder, the recommended alternative was therefore the MSK mechanical switch.
This is not simply a wiring modification.
It is a change in the sensor technology selected for the cylinder.
The reason is that the electrical interface required by the machine has to be compatible with the type of signal generated by the switch.
Why replacing the switch can be better than modifying the machine
When an older machine is designed around simple two-wire contact signals, modifying the machine’s electrical architecture to accommodate electronic three-wire sensors may be unnecessary.
Depending on the application, replacing the sensor with a compatible mechanical or reed-type switch can be a more practical solution.
The Vega Team followed exactly this approach in the technical case:
machine requires two-wire connection → current electronic switch is not compatible → select an alternative switch compatible with the machine.
This can be particularly useful when upgrading or maintaining older injection molding machines.
The machine input must be checked before selecting the switch
Before ordering a replacement switch, the electrical interface of the machine should be established.
The following questions are useful:
- Does the machine expect a simple dry contact?
- Does the input require two wires or three wires?
- Is the input designed for mechanical contacts?
- Is a power supply required by the sensor?
- Is the machine compatible with PNP or NPN electronic sensors?
- Is the signal normally open or normally closed?
- What voltage is used by the input?
- Does the machine require a particular switching technology?
The correct switch can then be selected based on the actual input configuration.
Vega’s more recent technical documentation follows the same principle: three-wire electronic sensors require a compatible electrical input, while older machine controls designed for mechanical contacts may require a different switch technology.
Why the sensor cannot always be treated as an independent component
A hydraulic-cylinder switch is part of a larger system:
Cylinder → Position detection → Electrical signal → Machine input → PLC → Machine sequence
If one element is incompatible, the complete chain may not operate correctly.
For example, a cylinder may reach the correct end position mechanically, but the machine may fail to recognize it because the sensor output is incompatible with the PLC input.
This can lead to symptoms such as:
- the machine waiting indefinitely for a position signal;
- a cylinder appearing not to reach its end position;
- an incorrect alarm;
- an incomplete automatic cycle;
- intermittent signal detection.
The problem may therefore be electrical rather than hydraulic.
Sensor selection also depends on cylinder construction
The type of position sensor cannot always be selected independently of the cylinder.
Vega’s current product documentation shows this clearly. For example, the MSU1 is specifically associated with the V215CR, while the MSU4 is associated with the V220CC.
Other Vega cylinders use different sensor technologies depending on their construction and configuration.
This means that, when replacing a switch, the following information should be available:
- cylinder model;
- cylinder version;
- bore;
- switch currently installed;
- machine input configuration;
- required signal type;
- operating environment.
This prevents the common mistake of ordering a sensor solely because its connector or external dimensions appear similar.
The importance of the official switch documentation
In the original technical exchange, the Vega Team explicitly referred to the official Vega switch datasheet attached to the email.
This is the correct approach when working with different generations of switches.
The datasheet should be used to verify:
- electrical configuration;
- wiring;
- contact type;
- voltage;
- current;
- connection method;
- mechanical compatibility;
- temperature limits.
Where the application involves an older switch or cylinder, archived technical documentation can be particularly important.
A practical decision process
When a Customer asks whether a cylinder switch can be connected to a two-wire machine, the following procedure can help.
Step 1 – Identify the cylinder
Determine the exact cylinder model and version.
Step 2 – Identify the switch
Determine whether the switch is:
- magnetic;
- Reed;
- inductive;
- mechanical.
Step 3 – Identify the machine input
Establish whether the machine requires:
- two-wire contact;
- three-wire electronic sensor;
- PNP output;
- NPN output;
- another specific interface.
Step 4 – Compare the two systems
Do not assume that a switch can be rewired simply because it physically has the required number of wires.
Step 5 – Select a compatible alternative if necessary
If the installed sensor is incompatible, replace it with a Vega switch designed for the cylinder and suitable for the machine’s electrical architecture.
Step 6 – Verify the wiring before commissioning
The final wiring should be checked against the appropriate technical documentation.
What this case teaches
The most important lesson from this technical case is that sensor compatibility is both mechanical and electrical.
A switch may fit correctly on a hydraulic cylinder and still be unsuitable for the machine.
Likewise, a three-wire mechanical switch may not require three wires in the machine connection: the common and normally open contacts may be sufficient.
The correct solution therefore depends on the specific combination of:
cylinder + switch + electrical input + wiring configuration.
Conclusion
Connecting hydraulic-cylinder position switches to an injection molding machine requires more than counting the number of wires.
In this technical case, the Vega Team determined that MSU1 and MSU4 could not be connected to a two-wire machine in their existing configuration, and therefore recommended alternative switches. Specific replacement paths were identified for MSU1, MSU2/MSU3 and MSU4.
For the mechanical switches used on CM cylinders and the MSK switch used on V260 cylinders, three wires were available, but only the common (C) and normally open (NO) contacts were required for connection to the machine.
The V260 MSJ inductive switches, on the other hand, could not be connected to a two-wire system, so the Vega Team recommended considering the MSK mechanical switch instead.
The key principle is therefore:
A hydraulic-cylinder switch must be selected according to both the cylinder and the electrical architecture of the machine.
Checking the sensor technology, wiring configuration and machine input before ordering can prevent incorrect connections, unnecessary modifications and delays during mold commissioning.
Useful and Verified Vega URLs
- Hydraulic Cylinder End-Stroke Switches — Official Vega overview of magnetic, inductive and mechanical switches for hydraulic cylinders.
- MSU1 Magnetic Switch for V215CR — Official Vega product page for the MSU1 magnetic switch used with the V215CR.
- MSU4 Magnetic Switch for V220CC — Official Vega product page for the MSU4 magnetic switch used with the V220CC.
- How to Connect Multiple Hydraulic Cylinder Position Sensors to a PLC — Vega technical article explaining the relationship between hydraulic-cylinder sensors, three-wire electronic switches, PLC inputs and the SIM08 connection system.
- Monitoring Hydraulic Cylinder Position Sensors on Injection Molds — Vega technical article covering sensor management, testing and the relationship between sensor technology and cylinder construction.
- Vega Support — Official Vega technical support article archive covering hydraulic cylinders, switches, sensors and spare parts.
