The MiniPLC system

Do you think that classic current loop consumes too much power? We have solution for you. PLC system with 0 - 5 mA current loop.

Key Features

The 5 mA ecosystem

Original 20 mA loop was invented in 50's in 20th century. Nowadays the electronics is more advanced, able to measure smaller currents and consumes lower power. The reason for usage 5 mA loop is 4-times or less power consumption. For example if you have 14 signals in 20 mA loop (which is possible with our MiniPLC), it could consume up to 280 mA in total which means dissipation of 6.7W in total only for these 14 loop inputs. With 5mA loop it will be only 1.7W in maximum.

There is also benefit in use of smaller voltage on loop. When you use 20mA loop, for 4-kOhm line you have to use 80V at least, for 5 mA loop you can use 24V.

The 5 mA loop-powered converters

We offer several converters for 5mA ecosystem:

What's about backward compatibility with 20 mA loop

It is possible to process 20mA signals with 5mA inputs. Only put 167Ohm resistor in parallel with input.

Event-driven language

MiniPLC offers different concept than usual PLC - instead of periodically run loop, there is event driven machine. On each change of the signal, the particular part of code is called, hence there is less overhead for more complex systems.

No special environment for programming needed

You can program MiniPLC only from notepad. Souce code is simply send via console and compiled directly on MiniPLC.

Writeback feature for runtime signals

You can select in your program which signals should be backed up and restored after power off. This is good when you use modbus protocol to set-up some variables.

Extensive debugging

Signal values of the state machine and hardwre can be explored via display, no laptop or other device needed. It is also possible to dump last received and transmitted packet, for debugging of modbus protocol.

Modbus supported

MiniPLC offers two serial ports for modbus. Both master and slave mode is supported.

Where to buy

As other our products, you can buy directly from us. Just write an e-mail to

5-mA loop-powered modules

RTD-to-current converter

It is intended to use with Pt1000, Ni1000, Ni5000 or KTY 81/210. Modules are very small (only 20x22 mm) so they can fit into most types of boxes.

Technical data

TypeSupply voltageInput rangeMinimal currentEquation
A12 - 48V0 - 4000 Ohm1mA I = R/1000 + 1 [Ohm, mA]
B12 - 48V0 - 20000 Ohm1mA I = R/5000 + 1 [Ohm, mA]

Thermistor-to-current module

It is inteded for use with 10k NTC thermistor element.

Technical data

Supply voltageInput rangeMinimal currentEquation
12 - 48V0 - inf Ohm1mA I = 10000/(R+10000)*4 + 1 [Ohm, mA]

Thermocouple-to-current module

It is inteded for use with thermocouples. Cold junction could be compensated using RTD module by MiniPLC.

Technical data

TypeSupply voltageInput rangeMinimal currentEquation
A12 - 48V-50 mV to +150 mV1mA I = U/50 + 2 [mV, mA]
B12 - 48V-10 mV to +30 mV1mA I = U/10 + 2 [mV, mA]

Other devices

Galvanically isolated voltage-to-current converter

Key features

Technical data

TypeSupply voltageInput rangeLoop currentEquation
A18 - 36V0 - 5V or +/- 2.5V0 - 5mA I = U or I = U + 2.5 [V, mA]
B18 - 36V0 - 5V or +/- 2.5V0 - 20mA I = U*4 or I = U*4 + 10 [V, mA]
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Monokrystaly, s.r.o, Přepeře 297, 512 61 Přepeře, Czech republic
Tel: +420 481 325 857, Tel/Fax: +420 481 313 200, Mobile: +420 775 325 857