UniPi Neuron L503 PLC represents an intermediate model of the Neuron 500 line, focused on an increased number of analog I/O. The L503 also features an additional RS485 serial line and is an enlarged variant of the M503 model
The product features an integrated Raspberry Pi 3 Model B computer
UniPi Neuron L503 is a universal control unit of the Neuron modular PLC product range, designed for control and regulation of smart building systems, HVAC systems, industrial automation and others. The unit can also be utilized for energy consumption monitoring, data collection and their cloud storage, or it is possible to use it as a gateway for other devices (boilers, heaters etc.).
The L503 is an intermediate model of the Neuron 500 line (consisting of the L503, M503 and L513 models) and as the rest of the 500 line, it features multiple analog I/O modules and additional RS485 universal bus port while retaining a set of digital and relay I/O capability. Multiple analog inputs can be used for automation tasks requiring either receiving of voltage or current signal for gathering data from corresponding sensors (such as resistance thermometers), while analog outputs are designed for control and regulation of external devices such as three-way valves or heat exchangers.
Digital inputs (DI) are used for reading 5-40V DC voltage pulses generated by various binary devices such as digital lightning switches, motion sensors, digital measuring devices (energy meters, flow meters, pressure meters) etc. Digital outputs of the M403 model also feature an in-built pulse counter.
Digital outputs (DO) are using 5-50V DC voltage pulses at 750mA max. current for switching various two-state devices such as door locks, shutter controls, automatic doors, heat pumps, lights etc. Digital outputs of Neuron controllers also feature the PWM (Power Width Modulation) function, allowing the output to transmit analog signal via binary modulated signal.
Relay outputs (RO) are using AC/DC voltage or current for switching two-state devices such as boilers, water heaters, electric motors or larger external relays. Neuron line relays are rated for max. 250V DC/30V AC voltage or max. 5A switchable current.
Analog inputs are operating with either 0-10V voltage or 0-20mA current signal for receiving data from corresponding sensors (such as resistance thermometers). The L503 (as well as other Neuron 500 controllers) is provided with two types of analog inputs. Group 1 analog input (AI1.1) does not feature the option to read data from resistance sensors, it can be however used for voltage or current measurement based on AI register settings. Group 2 analog inputs (AI2.1-AI2.4) then allow the user to perform a precise measurements of voltage, current or resistance based on current output register settings.
Analog outputs serves for regulating and controlling of various devices (three-way valves, heat exchangers, circulation pumps etc.) by 0-10V voltage or 0-20mA current signal. Group 1 analog output of the L503 (AO1.1) allows the user to set output voltage through corresponding AO register settings. This setting is performed by inserting 0-4000 value (equal to 0-10V voltage range) into the AO register.
More detailed info about I/O usage and settings can be found in Neuron technical documentation (see Files tab above).
In contrast to other Neuron models, the L503 features two RS485 serial lines for communication with external devices or for extension modules connection (such as the Neuron xS extension module line). Single RS485 line can communicate with up to 256 devices, the L503 can thus communicate with up to 512 devices, using two different communication protocols.
Included is also a single 10/100MBit Ethernet port for network communication and a single 1-Wire bus for connection of various 1-Wire sensors (such as digital thermometers). A single 1-Wire channel can communicate with up to 15 sensors at once.
Due to 1GB RAM and a 1.2GHz quad-core CPU, all Neuron models possess a very low response rate (ie. delay between input signal reception and output response) of approximately 0.5 ms, giving them a high level of performance.
All components are encased within a durable anodized aluminium case providing IP20 cover. The unit's size is 12 DIN modules, DIN rail holder is included in the package.
Neuron is CE and EMC tested and is compliant with all corresponding European PLC standards. In accordance with these standards Neuron can be used in:
The EU declaration of conformity can be found in the Files tab (see above).
Standard Neuron model overview
|Type S (size on DIN rail: 4 modules = 7 cm)||
4 × 1.2 GHz CPU
|Type M (size on DIN rail: 8 modules = 14 cm)|
|Type L (size on DIN rail: 12 modules = 21 cm)|
Extension modules (size on DIN rail: 4 modules = 7 cm)
Extension modules communicate over Modbus. It is possible to connect them to the control unit via RS485 interface. Extension modules are compatible with any control unit with the RS485 interface and Modbus support.
* features an integrated wireless GPRS module.
** features an integrated TR-76D smart IQRF transciever
|Dimensions||210 mm × 90 mm × 60 mm|
|CPU||4 × 1 GHz|
|RS485 interface||2 ×|
|1-Wire bus||Yes (galvanically isolated)|
|Power||24 V DC|
|RTC backup||maximum 7 days|
|Mounting||DIN (35 mm)|