DI-2108 CDC mode binary encoding

DI-2108 CDC mode binary encoding

I have a DI-2108 in CDC mode which I have recording a single channel with ASCII encoding.  When I try to switch to binary encoding (encode 0) I am not getting anything back from the unit.  Curiously, if I put it in binary mode and start logging, wait for a while, stop logging, then switch to ascii encoding (encode 1), it dumps a bunch of ascii readings before echoing the encode 1 response.

Is there some kind of additional handshaking required in binary mode that I've missed?

ASCII mode log:
DI-2108 Logger connected
Data Logger Test Routine
 Sending: stop..........
 Sending: ps 0
 ps 0
 Sending: encode 1
 encode 1
 Sending: filter 0 1
 filter 0 1
 Sending: slist 0 0
 slist 0 0
 Sending: deca 2
 deca 2
 Sending: dec 512
 dec 512
 Sending: srate 5859
 srate 5859
 Sending: start 0
  0.002
  0.002
Measurement Started
 0.646
 1.238
 1.292
 1.292
 1.292
 1.292
 1.292
 1.292
 1.292
 1.292

Binary mode log:
DI-2108 Logger connected
Data Logger Test Routine
 Sending: stop..........
 Sending: ps 0
 ps 0
 Sending: encode 0
 encode 0
 Sending: filter 0 1
 filter 0 1
 Sending: slist 0 0
 slist 0 0
 Sending: deca 2
 deca 2
 Sending: dec 512
 dec 512
 Sending: srate 5859
 srate 5859
 Sending: start 0
Time out waiting for data

Switching from encode 0 to encode 1
stop
stop
start 0
stop
stop
encode 1
-0.001
 0.176
 0.932
 1.278
 1.288
 1.288
 1.287
:
:
 1.287
 1.287
 1.287
 1.287
 1.288
 1.288
encode 1