Work around unsupported commands for the E-709 controller

[kmpeters]

The E-709 controller doesn't support the SRG command. It also doesn't support a command mentioned in the following #10 (comment).

The following issue was created in response to #10, but it doesn't explicitly mention the E-709:
#11

[kmpeters]

This issue is partially resolved by #21

[kmpeters]

This comment describes the unresolved part: #10 (comment)

Specifically, the E-709 controller does not support the parameter 0x07030600.