There are theoretical and methodological gaps in the B2B social media marketing communications literature. As a consequence, there is a need for new approaches that provide a comprehensive understanding of how B2B online marketing posts create virtual conversations and the types of meanings these linked communication events construct and convey, particularly as these message are often distributed across multiple social media platforms. This paper presents a Social Semiotic Multimodal (SSMM) framework that attempts to address shortfalls in theory and method conceptualisation of social media communications. This framework employs multimodal extensions to systemic functional linguistics enabling it to be applying to analysing non-language as well as language constituents of social media messages. Furthermore the framework also utilises expansion theory to identify, categorise and analyse various marketing communication resources associated with marketing messages and also to reveal how conversations are chained together to form extended online marketing conversations. This semantic approach is exemplified using a Fairtrade Australia B2B case study demonstrating how marketing conversations can be mapped and analysed. The framework emphasises the importance of acknowledging the impact of all stakeholders, particularly messages that may distract or confuse the original purpose of the conversation.