Gulliford, C.M. Bartnik, A.C. Berg, J.S. Dobbins, J. Nunez-delPrado, A. Sagan, D. JACoW Publishing Geneva, Switzerland 978-3-95450-200-4 10.18429/JACoW-ICAP2018-TUPAF10 English 196-201 TUPAF10 EPICS simulation lattice linac MMI Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-ICAP2018-TUPAF10 http://jacow.org/icap2018/papers/tupaf10.pdf The Cornell-Brookhaven CBETA machine is a four pass Energy Recovery Linac (ERL) with a Non-scaling Fixed-Field Alternating gradient (NS-FFA) arc. For online modeling of single particle dynamics in CBETA, a customized version of the Tao program, which is based upon the Bmad toolkit, has been developed. This online program, called CBETA-V, is interfaced to CBETA’s EPICS control system. This paper describes the online modeling system and initial experience during machine running.