Hello,

For creating barcode labels with the serial number you need to create a button in ' stock.lot ' model, please refer this below code for button function.

def generate_barcode(self):
    for record in self:
        data = {
            'response': record.name,
        }
        return self.env.ref('module_name.action_for_barcode').report_action(self, data=data)

In xml file in data folder, create a action for triggering this barcode

<record id="action_for_barcode" model="ir.actions.report">

    <field name="name">action_barcode</field>

    <field name="model">my.barcode</field>

    <field name="report_type">qweb-pdf</field>

    <field name="report_name">module_name.template_name</field>

    <field name="report_file">module_name.template_name</field>

</record>

And finally create a template for generating barcode

<template id="template_name">

    <t t-call="web.basic_layout">

        <div class="page">

            <div class="col-md-6">

                <img class="barcode" t-att-src="'/report/barcode/?barcode_type=%s&value=%s&width=%s&height=%s&humanreadable=1&quiet=0'

 % ('Code128',response, 205, 67)" alt="Barcode"/>

            </div>

        </div>

    </t>

</template>

in this way you can create barcode with serial number.

Regards