Food Trucks: Printing When the Uplink Is Not There

A truck's network is whatever it can find: a phone hotspot, an LTE router bolted under the counter, or a lot's guest Wi-Fi that a hundred other people are also on. That is a bad uplink to hang a receipt on — so the honest question is not "does this work on a truck", it is "which parts of it stop when the uplink does". This page answers that part by part, and it is specific about the two things that will actually cost you a service: power, and moving between networks.

The node is downstream of your uplink, not a replacement for it

A node joins a Wi-Fi network like any other client. There is no cellular radio in any declared hardware variant — not the board the Proxy Node Kit ships with, not the dual-band one, not the wired one. If your hotspot is the only way onto the internet, it is still the only way onto the internet.

What that costs you is much less than it sounds, because the print path does not go through it. Your point of sale sends the job over your own network — the hotspot's LAN counts — and the node drives the printer over USB. Nothing in that sentence involves the internet, and nothing in the firmware makes it involve the internet.

What keeps working with no uplink at all

The right-hand column is short on purpose, and one entry on it is worth saying out loud rather than burying: creative printing is the one feature that needs the internet, and it needs it every time. The node relays your sentence to the cloud with its own device token and prints what comes back — the model key stays in the cloud, the print path stays on your LAN, and with no uplink there is nothing to relay to. Everything else on the left keeps going.

What is only buffered, and for how long

If you have pointed a node at a telemetry receiver, it appends a heartbeat to a small in-memory ring on a schedule and flushes the whole ring in one upload. A 2xx clears what was sent; any other outcome — an error status, or no answer at all — keeps everything, so the next attempt goes out with the accumulated backlog.

The ring is bounded at 32 heartbeats, one a minute, and when it is full it drops the oldest record. So an outage costs you the beginning of the gap, not the end of it: after half a day parked somewhere with no signal, what reaches the receiver is roughly the last half hour, not the whole shift. That is a deliberate degradation rather than a bug — the alternative is a node that either blocks or grows without bound — but it is the kind of thing worth knowing before you build a report on it.

A node with no receiver URL and token configured buffers nothing and keeps nothing, not even locally. Telemetry is something you switch on.

Power is what will actually bite you

Two sentences from the troubleshooting page matter more on a truck than anywhere else, because a truck runs on an inverter behind an engine or a generator rather than on a building's mains:

• The board does not source 5 V. If a printer will not enumerate at all and no device event appears, the cable arrangement needs a powered leg.
• Give the node its own supply, and do not power it from the printer. "Prints, then the node reboots" is a brownout under head current, every time.

A node can power-cycle its own USB bus and escalate against a bus that has stopped answering — root-port cycles at 30 seconds, 2 minutes and 10 minutes, then a reboot rung, capped at six cycles in any rolling hour, and it says when it has reached the cap rather than going quiet.

Moving between networks

A truck changes networks the way a restaurant changes nothing. The setup path is built for that:

• An unprovisioned node opens its own setup Wi-Fi network and prints a QR slip with the join details on it. No laptop, no app, no IT visit.
• Type the password wrong and it self-heals back to setup on its own in about three minutes, rather than sitting there unreachable.
• If you cannot find it, a tap of the B button makes it announce itself as a Wi-Fi network whose name carries its id and its current address.

Full sequence, including the case where no printer is attached yet: the quickstart. When something is already plugged in and misbehaving, troubleshooting is the symptom-led version.

What you cannot do, stated before you find out

• There is no remote access to a node, and no path from our cloud into your network. From your kitchen table you cannot print to the truck, reach the node, or read its status. That is not a missing feature waiting on a release; it is the shape of the product. Everything above happens on site or not at all.
• We publish no uptime figures for the cloud layer, so do not plan a shift around one.
• ESC/POS is the only print language this firmware implements. If your printer answers something else, the node refuses the job by name rather than feeding a roll of garbage — see what we have tested.
• If your point of sale picks printers from a certified list instead of printing to an address you type in, that is the case that is not proven. The identities a node can advertise have never been accepted by a real point-of-sale system in our presence, and the compatibility page says so in the same words the firmware source does.

FAQ

Frequently asked questions

Will receipts print if my hotspot drops mid-service?

Yes, as long as your POS and the node are still on the same local network — a hotspot with no internet is still a network. The print path never leaves that network: your POS sends the job, the node drives the printer over USB, and nothing in between waits on a server.

Does the node need a SIM or its own data plan?

No, and it cannot use one. No declared hardware variant has a cellular radio. The node joins a Wi-Fi network as a client, so whatever you already use for the truck's internet is what it joins.

What happens to the telemetry I miss while offline?

It buffers on the device — 32 heartbeats, one a minute — and uploads in one batch when a receiver answers. Nothing is cleared until an upload is acknowledged. When the ring fills, the oldest record is dropped, so a long outage keeps the most recent half hour or so rather than all of it.

Can I check on the truck's printer from home?

No. There is no remote access to a node and no cloud path into your network, by design. An account shows you when a node was last seen and its address on its own network, which is a link you can open when you are there — not a way in from somewhere else.

The node keeps restarting when a big order prints. What is that?

Almost always the power supply, not the software. Head current on a thermal printer is spiky; if the node is drawing from the same marginal supply it browns out under load. Give the node its own supply and use a powered leg for the printer, then look at anything else.

Related: what to do when the internet takes your printing with it · kitchen printer setup · running nodes across several sites · more for operators at Proxy Nodes for restaurants.