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Nelko PM220 (T45R) Linux USB and Bluetooth Setup Guide

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https://nelko.com/pages/driver-user-manual

PM220.ppdDownload

Nelko PM220 (T45R) Linux Setup Guide: USB & Bluetooth

If you’ve struggled to get the Nelko PM220 (or similar T45R-chipset thermal printers) working on a modern Linux distro, this post is for you. We discovered that the “Golden Path” to a stable setup involves perfecting the USB connection first before moving to wireless.

1. The Mandatory First Step: USB Setup

Always get the printer working via USB before attempting Bluetooth. This ensures your driver and PPD are correctly configured without the added complexity of wireless permissions.

  • The Driver: Use the official PL70e Linux driver package. The rastertolabel binary in this package is the most stable engine for the PM220.
  • The PPD: Modify your PPD to point to the Nelko/Filter/rastertolabel filter.
  • Key Settings:
    • Ensure the Resolution line uses cupsColorSpace 0 (Grayscale) and cupsBitsPerColor 8.
    • Include *cupsModelNumber: 20 in the metadata.
    • If the printer works via USB but fails later on Bluetooth, you know the issue is a connection permission, not a driver fault.

2. Connecting via Bluetooth SPP

Once USB printing is successful, you can move to wireless by mapping the Bluetooth signal to a legacy serial device node.

  • Pairing: Use your system Bluetooth manager to pair with the PM220 (MAC: 31:9D:7B:7A:C1:9A).
  • The Serial Checkbox: Ensure “Serial Port” or “SPP” is enabled in your Bluetooth settings. This creates /dev/rfcomm0.
  • User Groups: You must add your user to the lp and dialout groups:

Bash

sudo usermod -a -G lp,dialout $USER

(Note: You must log out and back in for this to take effect.)

  • The Persistence Rule: Create a udev rule at /etc/udev/rules.d/99-pm220.rules so the lp group always owns the port:

Plaintext

KERNEL=="rfcomm*", GROUP="lp", MODE="0660"

3. The “Silent Gatekeeper”: AppArmor

Even with the correct groups, modern Linux security (AppArmor) often blocks the CUPS service from writing to Bluetooth nodes, resulting in a “Permission Denied” error.

The Fix:

  1. Edit the local CUPS profile:Bashsudo nano /etc/apparmor.d/local/usr.sbin.cupsd
  2. Add this permission line inside the file:Plaintext/dev/rfcomm[0-9]* rw,
  3. Reload AppArmor:Bashsudo systemctl reload apparmor

4. Configuring CUPS

Set your device URI to the serial node created by your Bluetooth manager.

  • Printer URI: serial:/dev/rfcomm0
  • CLI Setup Command:

Bash

sudo lpadmin -p Nelko_PM220_BT -v serial:/dev/rfcomm0 -E -P /path/to/your_modified.ppd

5. Troubleshooting & Maintenance

  • Testing the Pipe: Verify the Bluetooth link by bypassing CUPS and sending raw TSPL code:

Bash

echo -e "\x1b\x40\x0aSIZE 40 mm,30 mm\x0aPRINT 1\x0a" > /dev/rfcomm0
  • Baud Rate: Ensure the virtual port is set to 115200 in raw mode:

Bash

sudo stty -F /dev/rfcomm0 115200 raw -echo

Important: Paper Handling Behavior

The printer’s behavior when closing the lid depends entirely on the media used:

  • With Labels: The printer feeds slightly to calibrate, detects the gap, and sucks the label back in to the correct start position.
  • With POS (Continuous) Paper: Because there is no gap to detect, the printer feeds approximately 20cm of waste paper. This is a firmware-level self-test and cannot be overridden by the driver.