Odoo ePOS Receipt Printer Setup
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    • 🖨️ Epson TM-* Receipt Printer – Secure HTTPS Setup for Odoo POS


    Purpose

    To enable trusted HTTPS communication between Odoo POS and Epson TM-* printer, by installing a self-signed certificate that includes a valid IP-based Subject Alternative Name (SAN).

    📋 Prerequisites

    • A Linux/macOS system with openssl installed (or WSL on Windows)
    • Access to Epson printer web UI (http://192.168.x.x)
    • Admin access to the PC and printer

    🛠 Step-by-Step Instructions

    1. Create OpenSSL config file with IP SAN

    Save as epson_ip.cnf:

    [req]
    default_bits       = 2048
    prompt             = no
    default_md         = sha256
    distinguished_name = dn
    x509_extensions    = v3_req

    [dn]
    C = JP
    O = SEIKO EPSON CORP.
    CN = 192.168.123.210

    [v3_req]
    subjectAltName = @alt_names

    [alt_names]
    IP.1 = 192.168.123.210


    ** Update the IP address as needed (192.168.123.210 is used as an example here)

    2. Generate private key and certificate with SAN

    openssl req -x509 -nodes -days 3650 \
      -newkey rsa:2048 \
      -keyout epson.key \
      -out epson.crt \
      -config epson_ip.cnf \
      -extensions v3_req
    3. Package into a .pfx (PKCS#12) file

    openssl pkcs12 -export \
  -inkey epson.key \
  -in epson.crt \
  -out epson.pfx \
  -name "Epson IP Cert"
    • Set a password when prompted
    • Remember this password — you'll use it in the Epson UI

    4. Upload Certificate to Printer

    1. Go to: http://192.168.123.210 -> Printer IP
    2. Navigate to: Security → Server Certificate → Import 


    3. Upload the epson.pfx file

    4. Enter the password used during export
    5. Apply and reboot if required
    6. Set the Server Certificate
      Under SSL/TLS set the server certificate to CA-Signed Certificate, that was uploaded

     

    ✅ Verification

    • Visit https://printer-ip in browser
    • Certificate should show:
      • CN = IP address
      • SAN = IP address
    • No ERR_CERT_COMMON_NAME_INVALID in Chrome/Firefox

    🔐 Export the certificate from chrome

    https://www.odoo.com/documentation/18.0/applications/sales/point_of_sale/configuration/epos_ssc.html


    🔐 Trust the Cert in Windows

    1. Double-click epson.crt on Windows
    2. Click Install Certificate
    3. Choose Trusted Root Certification Authorities
    4. Finish wizard and restart browser

    Odoo POS will be able to communicate to receipt printers now.




    ⚠️ Why Not to Use Epson's Built-in Self-Signed Certificate

    The default self-signed certificate generated by Epson printers (like TM-T20II) should not be used as-is because:

    1. 🚫 No Subject Alternative Name (SAN)
      • Modern browsers (Chrome, Edge, etc.) require a SAN.
      • Epson’s built-in cert only has a Common Name (CN), which is ignored.
    2. ❌ Causes ERR_CERT_COMMON_NAME_INVALID
      • Even if the CN matches the printer IP or hostname, Chrome will reject it.
    3. 🔒 Breaks Secure POS Integrations
      • Browsers and systems refuse to trust the printer over HTTPS.
      • Odoo POS or other frontend apps may show security warnings or block requests.
    4. 🧱 Certificate Cannot Be Trusted or Replaced
      • You can’t upload a replacement cert unless it includes the private key.
      • Self-generated cert from Epson has a private key that cannot be exported.