Reports in the Midlands stated that the striker had travelled up to Yorkshire on Thursday afternoon to discuss personal terms and undergo a medical after both clubs reached an breakthrough regarding a fee after the Reds tabled a revised offer.
Should the deal go through, it will take Barnsley's number of summer recruits into double figures.
Earlier in the summer, Barnsley saw a £700,000 offer rejected for Worthing-born Chaplin, who the club were interested in signing last summer before he moved from Portsmouth to Coventry in a £500,000 deal.
The 22-year-old netted eight goals for the Sky Blues last term and should he move to Oakwell, he will link up again with ex-Coventry team-mate Luke Thomas, who spent last season on loan at the Ricoh Arena.
Barnsley have already brought in nine players so far in the close season, including wingmen Thomas and Mallik Wilks and attacking midfielder Mike-Steven Bahre, with the club still keen to add to their forward options.