MPS Series
MPS-8A4R-S
MPS-8A4R-S Industrial PLC Controller
MPS-8A4R-S is an industrial PLC controller with 8 isolated digital inputs and 4 relay outputs. Onboard RS-232, I²C, programmed in MP STUDIO ladder logic. DIN-rail mountable for automation, testing, HMI integration and machine control.
International shipping (EMS · DHL · UPS) — calculated at checkout by destination & weight
Ships the next business day (regardless of order time)
Large orders may take 1 extra day to dispatch
Cancel before dispatch · request a return/exchange after delivery
Key features
/ FEATURES- Programmed in MP STUDIO ladder logic
- 8 opto-isolated digital inputs (NPN/PNP, up to 40 V tolerant)
- 4 relay outputs for AC/DC dry-contact switching
- 6 analog inputs (0–5 V / 4–20 mA / 0–10 V ranges)
- 2 NTC temperature inputs (−40 to +120 °C)
- Industrial communication: RS-232, I²C · Modbus RTU
- DIN-rail 35 mm mountable, isolated field I/O for the factory floor
Specifications
/ SPEC| Power input | DC 12V – 24V |
|---|---|
| Digital inputs | 8 |
| Relay outputs | 4 |
| Analog inputs | 6 |
| Temperature sensor inputs | 2 |
| High-speed pulse inputs | 2 |
| High-speed pulse outputs | 3 |
| Encoder inputs | 2 |
| RS-232 | 1ch |
| I²C | 1ch |
| Modbus RTU | Yes |
| LS Cnet | Yes |
Software
MP STUDIO — Ladder Logic
The MPS series is programmed in MP STUDIO, a free ladder-logic IDE. Draw the control logic as a ladder diagram and call analog, temperature, high-speed counter and pulse output straight from function blocks.
Ladder logic only
Contacts and coils — existing PLC experience transfers directly
Function blocks
ADC · NTEMP · HCNT · ENCODER · PWM, each a single block
Live monitoring
Ctrl+T to download, Ctrl+M to monitor and debug on the machine
Before the first download
Install MP STUDIO from the ILOGICS download centre, pick your model in the device list, set the COM port, and you can download straight away.
Models that use the MP download cable appear in Device Manager as "USB Serial Port". If it does not appear, install the FTDI driver as well.
Connectivity
PC / HMI / Mobile
RS-232 serial talks to a PC or a touch HMI directly. Add the M-ETHER Ethernet converter and Modbus TCP opens the same data up remotely — from a PC, a touch HMI or a phone.
01Direct serial link
MPS-8A4R-S
RS-232 (CH1)
PC
SCADA / monitoring
Touch HMI
Operator panel
RS-232Modbus RTU SlaveLS Cnet
02Via the M-ETHER Ethernet converter
MPS-8A4R-S
RS-232 (CH1)
M-ETHER
Ethernet-to-serial converter
Sold separatelyMobile
Plant network / Wi-Fi
RS-232EthernetModbus TCP
Note: the MPS-8A4R-S provides one RS-232 channel (CH1) plus I²C; it has no built-in Ethernet port. Modbus RTU is supported as a slave, and Ethernet is available through the M-ETHER Ethernet converter. RS-485 is available by ordering the option that converts the RS-232 channel to RS-485.
Digital input
8 isolated digital input channels
8 digital input channels read external switches and sensors straight from the terminal block. In the ladder program they are the contacts P0–P7.
P0–P7 inputs
8 isolated digital input points in total
COM0 / COM1 commons
COM0 = P0–P3 · COM1 = P4–P7 (4 points per COM)
DC 0–40 V input
DC 5 V and above reads as HIGH · optocoupler isolated
NPN / PNP sensors
Either sensor wiring convention is read as-is
Input channel layout
* Example wiring for external switches or sensors — applying DC 12–24 V at the terminal turns that contact memory ON
Optocoupler isolation
The digital inputs use a bidirectional optocoupler stage — anti-parallel LEDs into a phototransistor — so either NPN or PNP wiring is read, and the field side stays electrically separate from the control circuit.
Example ladder — reading an input
P0 P32
0000 --| |---------------------------------( )--
P0 = push button (digital input), P32 = motor (relay output).
P0 ON -> P32 ON P0 OFF -> P32 OFFRelay output
4 isolated relay output channels, volt-free contacts
4 relay output channels switch external loads. Turning one of the output contacts P32–P35 on in the ladder closes that contact onto its COM — a volt-free contact, so it takes DC and AC loads alike.
P32–P35 outputs
4 isolated relay output points
Independent commons
Each of the 4 contacts has its own COM (an independent COM per point)
DC or AC loads
0–30 V D.C / 0–250 V A.C volt-free contact
Rated 5 A
Up to 5 A per point
Output channel layout
* Example wiring for external loads — the load supply comes in on the COM side. The relay contact is volt-free, so it may switch DC of either polarity or AC. The contact is rated 0–30 V D.C / 0–250 V A.C, up to 5 a per point. ⚠️ The relay coil runs on DC 24 V. Supply anything less and the relays never pull in — and USB power from the download port alone will not drive them either.
Relay output stage
The control circuit drives the relay coil, and the load is switched by a contact that is electrically separate from that coil. The contact carries no voltage of its own, so neither the type nor the polarity of the load supply matters.
Example ladder — driving a relay output
P0 P32
0000 --| |---------------------------------(S)--
P1 P32
0001 --| |---------------------------------(R)--
P0 = start button, P1 = stop button, P32 = motor on the relay output.
P0 ON latches P32 on (it stays on when P0 is released); P1 ON clears it.Analog inputAnalog Input
6 analog input channels + 2 NTC temperature channels on one 9-pin connector
6 analog input channels — the range is fixed per channel, not jumper-selected — plus 2 NTC temperature channels, all on a single 9-pin connector. The ladder reads them with the ADC and NTEMP function blocks.
AI0–AI5 · 6 channels
6 analog input points, 10-bit (0–1023)
Fixed range per channel
AI0/AI1 DC 0–5 V / 1–5 V · AI2/AI3 0–20 mA / 4–20 mA · AI4/AI5 DC 0–10 V
2 NTC temperature ch.
NTEMP channel 0 and 1 — NTC β-3950 10 kΩ (25°C)
−40 to 120°C · 0.1°C
Temperature resolution 0.1°C (over 0–40 °C)
9-pin analog connector
* Pins 1–6 AI0–AI5, pins 7–8 the NTC temperature channels, pin 9 GND. The square pad marks pin 1, and there is no V+ pin on this connector.
Per-channel input specs
| Channel | Input spec | Input resistance |
|---|---|---|
| AI0 · AI1 | DC 0–5 V / 1–5 V | 100 MΩ |
| AI2 · AI3 | 0–20 mA / 4–20 mA | 250 Ω |
| AI4 · AI5 | DC 0–10 V | 200 kΩ |
| NTC0 · NTC1 | NTC β-3950 10 kΩ (25°C) · −40 to 120°C | 10 kΩ pull-up |
Every analog channel is 10-bit (0–1023) and is read with the ADC function block. A 4–20 mA or DC 1–5 V sensor must be read with ADC2 instead, and its span is 0–818 rather than 0–1023. Running on the download port's 5 V alone makes that supply the analog reference, so use the external supply for precise measurement.
Example ladder — reading an analog input
@ON ADC
0000 --| |---------------[ CHANNEL:0 | MAX VALUE:1000 | MIN VALUE:0 | OUT:D0 ]--
@ON NTEMP
0001 --| |---------------[ CHANNEL:0 | OUT:D10 ]--
AI0's 0~5V arrives in D0 as 0~1000. For 4~20mA or DC 1~5V use ADC2 instead,
whose span is 0~818. NTC channel 0 lands in D10: 234 means 23.4 C, and a real
memory in OUT stores 23.4 directly.High-speed pulse outputPWM Output
3 PWM output points on one 4-pin header, all on TIMER1
PWM0–PWM2 come out on a single 4-pin header — 3 outputs plus a ground. The output swings DC 0 V LOW to DC 5 V HIGH at up to 30 mA per point, and the ladder drives it with the PWM, FPWM, FDPWM, NPWM function blocks.
3 PWM points
One 4-pin header · 3 outputs + GND
TIMER1, shared
All 3 points run on the one timer resource
DUTY / WIDTH 0–65535
Set the pulse directly, or give a frequency instead
DC 5 V · 30 mA
LOW DC 0 V / HIGH DC 5 V · up to 30 mA per point
Pulse output header and duty
* One 4-pin header, silkscreened PWM0, 1, 2, GND. The fourth pin is the ground the pulse output is referenced to.
Before you wire it
- PWM0, PWM1, PWM2 must all carry the same WIDTH — changing one changes all 3.
- Their frequency has to match too, for the same reason.
- FPWM, FDPWM, NPWM set TIMER1's WIDTH themselves to hit the frequency you ask for, so mixing them with the PWM block is not recommended.
- Used at the same time, FPWM / FDPWM / NPWM must share one FREQ. Used one after another, they may differ.
- DUTY may not exceed WIDTH. The smaller the WIDTH, the higher the output frequency.
- NPWM takes 0–60 kHz, and 30 kHz or below is recommended.
Pulse function blocks
| Function block | What it does | Parameters |
|---|---|---|
| PWM | Pulse by duty and width | PORT 0–2 / DUTY 0–65535 / WIDTH 0–65535 |
| FPWM | Pulse by frequency (50% duty) | PORT 0–2 / FREQ 0–1 MHz |
| FDPWM | Pulse by frequency and duty ratio | PORT 0–2 / FREQ 0–1 MHz / DUTY % |
| NPWM | Emit a set number of pulses | PORT 0–2 / FREQ 0–60 kHz / N 0–2,147,483,647 |
| POFF | Stop the pulse output | PORT 0–2 |
The output is LOW DC 0 V / HIGH DC 5 V at up to 30 mA per point. All 3 points share TIMER1, so their WIDTH and frequency have to match. Whether a port is currently emitting is readable from the special memory @PWM0–@PWM2.
Example ladder — PWM output
P0 PWM
0000 --| |-----------------------[ PORT:0 | DUTY:500 | WIDTH:1000 ]--
P1 POFF
0001 --| |-----------------------[ PORT:0 ]--
P0 FPWM
0002 --| |-----------------------[ PORT:1 | FREQ:1000 ]--
P0 FDPWM
0003 --| |-----------------------[ PORT:2 | FREQ:2000 | DUTY:70 ]--
PWM sets the pulse directly; FPWM emits a 50% duty at the frequency asked for,
and FDPWM adds a duty ratio. P1 stops port 0. PWM0~PWM2 share one timer, so
their WIDTH and frequency always match.High-speed counter · encoderCounter · Encoder
2 channels, up to 50kHz, counting pulses or tracking an encoder
Two channels count fast pulses or follow a quadrature encoder without the ladder scan having to keep up. Channel 0 is the FND/ENCO connector and channel 1 the I2C one; the ladder reads either with the HCNT and ENCODER function blocks.
2 counter channels
Channel 0 on FND/ENCO, channel 1 on I2C
Encoder A and B phases
B lagging A on A's rising edge counts up; leading counts down
4.7 kΩ pull-ups built in
Both channels carry it on the board
50kHz · DC 0–5 V
Up to 50kHz at an operating input of DC 0–5 V
What the two channels are for
* Both channels carry a 4.7 kΩ pull-up on the board, so a sensor with an open-collector output needs no resistor of its own. Channel 0 recognises HIGH at DC 3 V or above.
Counter and encoder connectors
* Channel 0 comes out on the FND/ENCO connector and channel 1 on the I2C one. The A and B marks under the signal poles are the encoder phases those poles carry.
Before you wire it
- Using channel 1 takes the SDA and SCL lines, so I²C communication cannot be used at the same time — they are physically the same pair.
- Channel 0's CLK and DIO are the same two poles a 7-segment (FND) display is wired to, on the same FND/ENCO connector.
- The operating input range on both channels is DC 0–5 V.
- These channels are not isolated. Isolated field signals belong on the digital inputs.
Channels and function blocks
| Channel | Connector | Built-in resistor · HIGH |
|---|---|---|
| Channel 0 | FND/ENCO | 4.7 kΩ pull-up · DC 3 V or above |
| Channel 1 | I2C | 4.7 kΩ pull-up · GND (LOW) |
| HCNT / HRST | Block | Read the counter · reset it |
| ENCODER / ENMOV | Block | Read the encoder · preset it |
| Both channels | Input rating | 50kHz · DC 0–5 V |
Channel 0 is CLK(A) and DIO(B); channel 1 is SDA(A) and SCL(B). The plain counter runs on CLK and SDA respectively, while the encoder uses both poles of whichever channel it is on. Both take up to 50kHz at an operating input of DC 0–5 V. Direction is decided on the A phase's rising edge: a B phase that lags counts up, one that leads counts down.
Example ladder — reading the high-speed counter
@ON HCNT
0000 --| |-----------------------[ CHANNEL:0 | OUT:D100 ]--
P0 HRST
0001 --| |-----------------------[ CH:0 ]--
@ON is always on, so the counter free-runs and D100 always holds the count.
P0 = the reset button; HRST clears channel 0 back to zero.Example ladder — reading and presetting the encoder
@ON ENCODER
0000 --| |-----------------------[ CHANNEL:0 | OUT:DD0 ]--
P0 ENMOV
0001 --| |-----------------------[ CHANNEL:0 | IN:100 ]--
DD0 is a double word, so the encoder count can run past a single word.
ENMOV writes a value INTO the encoder: here P0 presets channel 0 to 100.CommunicationRS-232 · I²C
One RS-232 channel and one I²C channel
RS-232 comes out on a screw terminal as TX, RX and GND for a 1:1 link to a PC or an operator panel, and it speaks Modbus RTU as a SLAVE. I²C is a master-mode channel with its pull-ups already on the board, for a DS3231 RTC or a character LCD.
RS-232 · 1 channel
1:1 link on the TX · RX · GND poles of CH1: RS-232
Modbus RTU slave
Slave only — this board does not act as a Modbus master
I²C · 1 channel
Master mode · 1:N · 4.7kΩ pull-ups built in
RS-485 as an order option
A standard board ships as RS-232. Select the communication-change option when ordering to have it built as RS-485, or use the M-CONV converter module.
I²C connector
* The I²C connector is silkscreened I2C and reads GND · 5V · SDA · SCL. It is a master-mode channel supporting 1:N, and its 4.7kΩ pull-ups are already fitted, so a DS3231 RTC or a character LCD connects with no external resistors.
RS-232 link
* The 4-pole screw block standing at the board's lower right, in the order TX · RX · +5V · GND from the top. RS-232 is a 1:1 link, so TX goes to the other device's RX and RX to its TX. The (+) and (−) marks are the A / B labels those two poles take when the board is ordered with the communication-change option. Ethernet is not on the board: an M-ETHER converter (sold separately) on this channel translates Modbus TCP/IP to Modbus RTU and also allows remote download and debugging.
Communication channels
| Channel | Connector | What it supports |
|---|---|---|
| I²C · 1 channel | 4-pin header | Master only · 1:N · 4.7kΩ pull-ups |
| RS-232 · 1 channel | CH1 · 3 poles | 1:1 link · Modbus RTU slave |
| Cubloc Modbus RTU | RS-232 | Slave · Comfile HMI |
| LS Cnet (XGK) | RS-232 | Slave · LS, M2I, Cimon HMI |
| IBUS | RS-232 | Master / slave · extends I/O |
| RS-485 | Order option | Built as RS-485 instead |
The specification publishes two communication channels: I²C and RS-232. Modbus RTU, Cubloc Modbus RTU and LS Cnet (XGK) are all supported as a SLAVE; IBUS runs as either master or slave and is what extends the I/O point count. The fourth pole of the serial block is a 0.5A supply output, not a signal.
Before you wire it
- Modbus RTU is supported as a slave only — this board cannot act as a Modbus master.
- Using the high-speed counter or encoder on channel 1 takes the SDA and SCL lines, so I²C cannot be used at the same time.
- There is no Ethernet port on the board. Modbus TCP/IP needs the M-ETHER converter (sold separately) on the RS-232 channel.
- RS-485 is a build-time option: select the communication-change option when ordering rather than changing the transceiver in the field.
- The +5V pole of the serial block is a supply OUTPUT rated 0.5A or less, not a communication line.
Display connectionLCD · FND
Show values on a character LCD or a 7-segment display — four wires either way
A character LCD goes on the I²C 4-pin connector and a 7-segment (FND) display on the FND/ENCO 4-pin connector. Both connectors bring out 5V and GND beside the two signal lines, so the whole run is four wires, and the I²C pull-ups are already on the board.
Character LCD 1602 · 2004
16 × 2 or 20 × 4 characters over I²C
7-segment (FND)
CLK and DIO on the FND/ENCO connector
4.7 kΩ pull-ups built in
No external resistors to add for I²C
1:N on I²C
Shares the bus with accessories such as the DS3231 RTC
Character LCD on I²C
* The I²C connector is silkscreened I2C and reads GND · 5V · SDA · SCL, with 4.7 kΩ pull-ups already on the board. The 1602 shows 16 characters over 2 lines and the 2004 shows 20 over 4. For a richer display than a character LCD, a touch HMI connects over the serial port instead.
7-segment (FND) on FND/ENCO
* The connector is silkscreened FND/ENCO and reads CLK · DIO · GND · 5V; the A and B marks under CLK and DIO are the encoder phases the same two poles carry. The display comes in a decimal-point form and a time-displaying form.
Before you wire it
- Using the high-speed counter or encoder on channel 1 takes the SDA and SCL lines, so I²C — and with it the character LCD and the RTC — cannot be used at the same time.
- The FND/ENCO connector's CLK and DIO poles are also the high-speed counter and encoder's channel 0 inputs — the 7-segment display and that channel share the same two poles.
- The signal poles on that connector are DC 0–5 V inputs.
- The character LCD, the 7-segment display and the RTC module are accessories sold separately — none is included with the board.
Displays and their connectors
| Display | Connector | Signals |
|---|---|---|
| Character LCD 1602 | I2C 4-pin | 16 × 2 characters |
| Character LCD 2004 | I2C 4-pin | 20 × 4 characters |
| 7-segment (FND) | FND/ENCO 4-pin | Decimal-point and time forms |
| I²C pull-ups | On the board | 4.7 kΩ · master mode, 1:N |
| DS3231 RTC | I2C 4-pin | Real-time clock |
Both connectors carry 5V and GND alongside the two signal lines, so a display needs no supply of its own. I²C runs in master mode, supports 1:N and has its pull-ups fitted on the board, so a character LCD can share the bus with another I²C accessory such as the DS3231 RTC. Character LCDs and 7-segment displays are sold separately.
Power · Data retentionPower · Backup
DC 12V ~ 24V in, 5 V out — and your data survives the blackout
The controller takes DC 12V ~ 24V and converts it to 5 V internally with an on-board regulator. Size the supply for at least 24V 0.5A.
DC 12V ~ 24V
Size the supply for 24V 0.5A or more
5 V internal
On-board regulator conversion
+5 V out 0.5A
From the +5 V pole of the RS-232 terminal block
Supercapacitor hold-up
About ten seconds on the +5 V pole
Before wiring the supply
- An EEPROM section written about 100,000 times can fail, and a failed section reads back a random value after a power cut. For values that change constantly, use the methods below.
- On USB power the controller runs but the relays do not: the coils are 24 V DC, so 24 V has to reach the power input before an output can close.
- Running on USB alone makes the USB 5 V the analog input's reference, so readings can wander. Use the external supply for precise measurement.
- Do not exceed the stated input voltage range.
- Do not reverse the supply polarity or mis-wire the input.
Where the power goes
* Either source runs the controller: the external supply through the regulator, or the download port's 5 V directly. The supercapacitor sits on the same 5 V node and keeps it alive when both go away.
Power and data retention
| Input voltage | DC 12V ~ 24V |
|---|---|
| Recommended supply | 24V 0.5A or more |
| Internal conversion | Regulator to 5 V |
| +5 V output | 0.5A max, from the +5 V pole of the RS-232 terminal block |
| USB-powered operation | Runs on the PC's 5 V through the download port |
| Non-volatile memory | EEPROM, about 100,000 writes per section |
| Hold-up on a power cut | Supercapacitor on the +5 V pole, about ten seconds |
| Blackouts retained | More than 100,000, writing only when the mains drops |
Size the supply for 24V 0.5A or more, plus whatever the +5 V pole is feeding (up to 0.5A).
Keeping data through a blackout
Which method you want depends on how often the value changes. The first two are settings; the third needs one part and a few rungs.
EEPROM retentive area — values that change occasionally
Mark a retentive area under Settings → Data Memory in MP STUDIO and the runtime copies that memory into non-volatile EEPROM every time its value changes — no code to write. Because a section survives only about 100,000 writes, it belongs to setpoints, calibration data and machine configuration rather than to anything the scan updates.
T EEPROM INTERVAL — timer memory
Timer (T) memory changes constantly, so the same settings window carries a T EEPROM INTERVAL. Set a period and the timer values are stored once per period instead of on every change, which is what keeps the write count down.
Supercapacitor — values that change constantly
Fit a supercapacitor to the +5 V pole and the internal 5 V stays up for about ten seconds after the main supply is cut. Wire the main supply into a digital input as well, add a rung that moves the live value into the retentive memory the moment that input goes off, and a second rung that moves it back once on restart. The EEPROM is then written only at the instant of a blackout, so it survives more than 100,000 of them.
Mounting · DIN railDIN Rail
Clips onto a 35 mm DIN rail, or screws down through the PCB's own holes
Inside a control panel the board clips onto a 35 mm DIN rail; built into a machine it screws down through the Ø3.5 mounting holes in the PCB. The board measures 77.0 × 100.0 mm without the rail clip, and stands 114.16 mm high once the clip is closed on the rail.
35 mm DIN rail
Clips onto the rail in a control panel
Direct PCB mounting
Screws through the Ø3.5 mounting holes
77.0 × 100.0 mm
PCB outline with no rail clip fitted
114.16 mm engaged
119.42 mm with the clip open, 114.16 mm closed
Mounting and dimensions
| Mounting | 35 mm DIN rail, or direct to PCB (Ø3.5 holes) |
|---|---|
| DIN rail | 35 mm |
| PCB alone (no clip) | 77.0 × 100.0 mm |
| Mounting holes | Ø3.5 mm · 60.2 × 90.0 mm apart |
| Clip open (before engaging) | approx. 119.42 × 60.2 mm |
| Clip closed (engaged) | approx. 114.16 × 60.2 mm |
Where no DIN rail is used, the board screws down through the Ø3.5 mounting holes in the PCB; on a rail, the clip closes over a 35 mm profile and the assembly stands 114.16 mm high.
Mounting on a 35 mm DIN rail
* The clip hooks over a 35 mm DIN rail. Overall height is 119.42 mm with the clip open and 114.16 mm once it is closed and engaged. The drawing shows the mounting method rather than the clip's own shape.
Outline and mounting holes
* The outline and mounting holes with no rail clip fitted. All dimensions in millimetres.
Installation notes
- Indoor use only. Do not install where there is rain, dust, frost, direct sunlight or condensation.
- Do not install in an atmosphere containing flammable or explosive gas.
- Do not install where there is heavy vibration or shock.
- Where the equipment affects life or property (nuclear, medical, marine, vehicle, aviation and the like), a secondary safety device must be fitted.
Downloads
/ FILESFAQ
How many I/O points does the MPS-8A4R-S have?▾
The MPS-8A4R-S provides 8 isolated digital inputs and 4 relay outputs, with onboard RS-232, I²C communication. See the specification table for the full breakdown.
Does the MPS-8A4R-S support Modbus RTU?▾
Yes. The MPS-8A4R-S supports Modbus RTU — master and slave alike — over its serial interface.
