Technical reference
Wiring
The supply is a standard enclosed switching power supply with a screw terminal strip. This page covers the mains side, the DC side, and what to check before you switch on. Signal wiring (RS-485, Ethernet) arrives with the unit and is covered in the register map page for addressing.
The L and N terminals carry 220 V AC. Isolate the circuit at the breaker before touching the strip. Connection should be made by a qualified electrician to the local wiring code. The earth terminal is not optional: the housing must be earthed before the supply is energised.
Terminal strip
Left to right: mains input, protective earth, then the DC output pair (COM / +V). The two COM terminals and the two +V terminals are internally the same node, so you can use either.
Mains input
| Terminal | Meaning | Notes |
|---|---|---|
L | Live (AC) | L and N are not polarity-sensitive on this supply. Either wire can go to either terminal. |
N | Neutral (AC) | |
PE | Protective earth | Bond to the enclosure. Do not leave floating. |
Use a fuse or breaker appropriate to the supply's input rating. The earth conductor should be at least as thick as the live and neutral conductors.
DC output
| Terminal | Meaning | Notes |
|---|---|---|
+V | DC positive | To the display's positive input. Two terminals, same node — one is a spare. |
COM | DC negative (0 V) | Common / return. Two terminals, same node. |
ADJ | Output voltage trim | Small potentiometer beside the strip. Set the output to the panel's rated voltage before connecting the display. |
Reverse connection: the supply has output protection, but do not rely on it. Check polarity with a meter first. If nothing lights up on first power-up, disconnect and verify polarity rather than re-flashing or rewiring the panel.
Alternative supply: DC 12/24 V input
Where there is no 220 V mains — a vehicle, a battery bank, a 24 V control cabinet — the panel can be fed from a DC-DC converter instead. Input accepts 12 V or 24 V; output is 5 V, 10 A maximum (50 W).
On the mains side, L and N can be swapped. Here they cannot. Reversing the input on a DC-DC converter can destroy it instantly, with no protection to fall back on. Verify with a meter before connecting, and mark the positive conductor.
| Terminal | Meaning | Notes |
|---|---|---|
+ (input) | DC positive | 12 V or 24 V nominal. Mark this conductor before you run it. |
− (input) | DC negative | Return from the battery or cabinet supply. |
− (output) | 5 V return | To the panel's negative input. |
+ (output) | 5 V positive | To the panel's positive input. |
Output is 5 V at 10 A maximum, 50 W total. Check the panel's rated current against that before choosing this supply — a large multi-line panel can exceed it. If it does, use the AC supply instead.
Before you switch on
- Earth bond is tight and continuous to the enclosure.
- No strand of the mains conductor is loose at the strip — check both L and N.
- With the display disconnected, power up the supply alone and measure the output: it should read the panel's rated voltage within tolerance. Turn ADJ if it does not.
- Power down, wait for the output LED to go out, then connect the display.
- Power up and confirm the display boots before connecting any signal cable.
Setting the output voltage with the display connected risks over-volting the panel if the trim is wrong. Do it unloaded, once, and leave it.
Signal wiring
The mains side is universal. The signal side depends on which protocol you are using, and the terminal positions differ between control cards.
| Interface | What to connect |
|---|---|
| Modbus RTU | RS-485 A / B pair, plus a common if the run is long. Two wires, twisted pair. |
| Modbus TCP | Ethernet to the plant switch. Panel listens on port 502 when configured as server. |
| MQTT | Ethernet or Wi-Fi to the broker. See the MQTT page for topics and payloads. |
RS-485, two-wire
Modbus RTU runs on a single twisted pair. Everything on the segment shares those two wires; only the addressing separates the devices.
TIA/EIA-485 defines A as the inverting line and B as the non-inverting one, but a large number of devices label them the other way round. If the link does not come up, swap A and B before you suspect anything else — it is by far the most common cause of a dead RS-485 segment, and swapping cannot damage either end.
| Wire | Purpose | Notes |
|---|---|---|
A | Differential pair, one side | Both wires must run in the same cable as a twisted pair. Do not use two separate single wires. |
B | Differential pair, other side | |
GND | Signal reference | Optional on short runs indoors. Recommended where the two ends sit on different supplies, or the run is long. |
Termination resistors (120 Ω across A and B at each end) apply to long segments or high baud rates. For a short run in one cabinet they are usually unnecessary — if you add them, only the two physical ends of the segment get one, never the middle nodes.
Ethernet, RJ45
Modbus TCP and MQTT over Ethernet both use a standard RJ45 port. Any normal patch lead works.
Straight-through leads for everything: the port auto-senses polarity, so crossover cables are unnecessary. A shielded lead is worth it in a cabinet next to a drive, but the shield is only useful if it is bonded at one end.
Terminal positions for the signal connectors are printed on the board silkscreen and repeated in the drawing supplied with each unit. Register addressing is on the register map page.
Ask for the drawing for your model