Citizen CT-S310II setup guide: from unboxing to first receipt

This guide takes a new Citizen CT-S310II from the box to its first receipt. It is written for our model CTS310IIEBK, the black European version with USB and RS-232 serial ports, and also helps with the other CT-S310II versions.

Before you start

Check which model you have

Citizen's user manual explains the letters after the model name. The first part is the interface: no letters means USB and serial, ET means Ethernet and USB. Then comes the market (E for Europe) and the case colour (BK for black, WH for cool white, PW for pure white). So CTS310IIEBK is the USB and serial version for Europe in black.

The interface is fitted at the factory: Citizen lists serial and wired LAN as factory options, its manual gives no way to change them, and Citizen offers no add-on LAN board for the CT-S310II. So you cannot add Ethernet to a USB and serial printer later. If you need network printing, contact us before you order. Connect only one interface cable at a time: Citizen warns against using several interfaces together.

Check the box

Citizen lists these items:

• The printer and the AC power cord
• A USB cable (only in some markets)
• A sample paper roll
• The 58 mm partition
• Four rubber feet for vertical use
• A power switch cover
• A wall-mounting bracket kit
• The quick start guide

Keep the partition even if you print on 80 mm paper today. Something missing or damaged? Contact us before you set up the printer.

Choose a spot

• The printer can stand flat, stand upright with the rubber feet, or hang on a wall. Citizen asks that a service person mounts it on a wall.
• Upright, fit the four rubber feet in the square recesses on the back. Don't pull the paper before it is cut, or the printer can tip over.
• Standing flat, use partial cuts only. Citizen warns that full cuts can cause cutter jams in this position.
• Keep it between 5 and 45 °C and 10 to 90 % relative humidity, without condensation.

Connect the power and the cables

Connect and disconnect cables only while the printer is switched off.

1. Make sure the power switch is off.
2. Plug the AC power cord into the AC inlet at the back of the printer. There is no separate adapter: the power supply is inside.
3. Connect the interface cable you will use, USB or serial, the right way round. A serial cable must be a 9-pin female to 9-pin female cable with Citizen's pin layout.
4. Connect the cash drawer cable now if you use one (see the drawer step below).
5. Plug the power cord into a wall socket.

When you unplug a cable later, hold the connector, not the cable.

Load the paper roll

1. Switch the printer on.
2. Pull the cover open lever forward and open the paper cover. Remove the empty core, if there is one.
3. Drop the roll into the paper compartment with the printable side facing down, as shown in Citizen's manual.
4. Pull a few centimetres of paper straight out of the printer.
5. Close the paper cover until it clicks. With the factory settings the printer feeds and cuts the paper by itself.

Use thermal paper 80 mm wide (or 58 mm with the partition), on a roll up to 83 mm in diameter. On the usual 12 mm core the paper should be 65 to 75 µm thick. Don't use rolls whose paper is glued to the core, or creased or folded paper.

Run a self-test

The self-test shows that the printer, the paper and the cutter work before you involve a computer.

1. Check that paper is loaded and the paper cover is closed.
2. Switch the printer off.
3. Hold down FEED and switch the printer on. Keep FEED pressed for about one second, then release it.
4. The printer prints its model name, firmware version, memory switch settings and a list of its fonts.

Keep this printout. It shows the current serial settings and paper width, which you need later.

Install the Windows driver

Citizen's driver for this printer is called "Windows Driver". It supports Windows 11, Windows 10 and Windows Server 2016 and 2019.

1. Open the Citizen drivers and tools page for the CT-S310II and download the Windows Driver. The same page has a Driver Install Guide.
2. Unzip the file and run the installer with administrator rights.
3. Follow the installer and select the CT-S310II and the port you use: USB or the COM port of the serial cable.
4. Finish the installer and restart the computer if it asks you to.

The same page offers OPOS, JavaPOS and POS for .NET drivers, a virtual COM port (VCOM) driver, CUPS drivers for macOS and Linux, and the POS Printer Utility. Your POS software supplier will tell you which one it needs.

Connect by USB or serial

USB

1. Connect the USB cable to the printer and to the computer.
2. Switch on the printer. Windows uses the Citizen driver you installed.

Using two or more CT-S310II printers over USB on one computer? Citizen says you then need to change the USB serial number so each printer is unique. Contact us if you need help with this.

Serial (RS-232)

1. With the printer off, connect the serial cable and tighten the connector screws.
2. Switch on the printer.
3. Set the same values in the driver or POS software as in the printer. From the factory the printer uses 9600 bit/s, 8 data bits, no parity, 1 stop bit and DTR/DSR flow control. Your self-test printout shows the current values.

Connect a cash drawer (optional)

1. Switch the printer off.
2. Plug the drawer cable into the cash drawer kick-out connector at the back of the printer, the right way round.
3. Remove the ground screw next to it and fix the drawer's ground wire to the printer with that screw.

The printer drives the drawer with 24 V. Use a drawer with a solenoid of at least 24 Ω (maximum 1 A). The port can drive two drawers, but not both at the same time. Never connect a telephone line to this port. You choose when the drawer opens in your POS software or the printer driver.

Change settings with the memory switches

The CT-S310II has no DIP switches. All settings are memory switches, which you change with FEED and the printouts, or with Citizen's POS Printer Utility.

Quick setting mode

This mode sets the three basics: model, paper width (80 or 58 mm) and character spacing.

1. Load paper and switch the printer off. Open the paper cover.
2. Hold FEED and switch the printer on.
3. Press FEED three times, then close the paper cover. The printer prints "Model" and the current choice.
4. Press FEED briefly to step through the choices. Hold FEED for two seconds or more to select the one printed last. The next item prints.
5. When "Save To Memory" prints, hold FEED for two seconds or more. The printer saves the settings and prints a list.

Individual setting mode

For single settings such as print density, print speed, buzzer, code page or serial values, use the same start but press FEED twice instead of three times. The printer then steps through "Memory SW (1)" to "Memory SW (10)" and "Save To Memory". The full list is in section 5.3 of the CT-S310II user manual.

Print a test receipt

1. On Windows 11, open Settings › Bluetooth & devices › Printers & scanners and select the CT-S310II.
2. Open the printer properties and click "Print Test Page". It prints as a receipt.
3. Print a receipt from your POS software to check the layout, the cut and the drawer.

Problems? See CT-S310II lights and printing problems, or all CT-S310II guides.

Using 58 mm paper

1. Switch the printer off and open the paper cover.
2. Fit the included partition in the slot that matches the 58 mm roll.
3. Load the 58 mm roll and close the cover.
4. Set the paper width to 58 mm in quick setting mode (see above), so the print fits the narrower paper.
5. Also select 58 mm paper in your driver or POS software.

For 80 mm rolls, Citizen's manual says to remove the partition. Unlike Epson, Citizen gives no warning against going back to 80 mm after using 58 mm paper. Set the paper width to 80 mm again after you remove it.