Warriors number eight Beattie returned to action against Munster two weeks ago but he turned out for Ayr last weekend after a registration error prevented his participation in the Heineken Cup with the pro team.
He and Ulster's Danielli missed the autumn Tests due to shoulder injuries and their return will be a boost for Robinson, whose team have home games against Wales on Saturday 12 February, Ireland on Sunday 27 February and Italy on Saturday 19 March.
"There's always excitement in the air at this time of year as we look forward to the RBS 6 Nations Championship," said the coach.
"I've been impressed by Robert Harley since I first saw him play in a pro-team back-up game some seasons back.
I've said often enough that players who perform for Scotland A are very much in the frame
Scotland coach Andy Robinson
"He has performed consistently for Glasgow this season in a position where we have strength and there is considerable competition for a starting place.
"Jon Welsh is another who has benefited from raising his game in the face of intense competition and has a good work ethic.
"Jack Cuthbert has had a really good couple of months having won his place in the Bath first XV. He was also on duty during the Nations Cup in Romania last summer and I've said often enough that players who perform for Scotland A are very much in the frame."
Some squad members will play for Scotland A against the Irish Wolfhounds in Galashiels on Friday 28 January.
But injury has ruled out Glasgow's Chris Cusiter and Graeme Morrison, Gloucester's Alasdair Dickinson and Jim Hamilton and Edinburgh's Phil Godman.
In last year's Six Nations, Scotland lost to France, Wales and Italy before results improved - they drew 15-all with England at Murrayfield and then secured a dramatic late win over Ireland at Croke Park.
Since then, the Scots have been buoyed further by two wins over Argentina in their summer tour and autumn Test victories over South Africa and Samoa, those last two helping to eradicate a Murrayfield thrashing by New Zealand.
Scotland squad: Backs - Joe Ansbro (Northampton Saints), Mike Blair (Edinburgh), Jack Cuthbert (Bath), Simon Danielli (Ulster), Nick De Luca (Edinburgh), Max Evans (Glasgow Warriors), Alex Grove (Worcester Warriors), Ruaridh Jackson (Glasgow Warriors), Greig Laidlaw (Edinburgh), Rory Lamont (Toulon), Sean Lamont (Scarlets), Rory Lawson (Gloucester), Dan Parks (Cardiff Blues), Chris Paterson (Edinburgh), Hugo Southwell (Stade Francais) and Nikki Walker (Ospreys).
Forwards - John Barclay, Johnnie Beattie (both Glasgow Warriors), Kelly Brown (Saracens), Geoff Cross, Ross Ford (both Edinburgh), Richie Gray, Dougie Hall, Robert Harley (all Glasgow Warriors), Nathan Hines (Leinster), Allan Jacobsen (Edinburgh), Alastair Kellock (Glasgow Warriors), Scott Lawson (Gloucester), Moray Low (Glasgow Warriors), Scott MacLeod (Edinburgh), Euan Murray (Newcastle Falcons), Ross Rennie (Edinburgh) and Richie Vernon and Jon Welsh (both Glasgow Warriors).
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