Send the following command
in the response string returned.
Response (String, string, 0, string)
A message containing four fields separated by commas, as follows:
2. Model number (5700A or 5720A)
3. Serial number
4. Three firmware versions: one each for the Main CPU, the Inguard CPU, and the Boost CPU. Each version is separated by a plus (+). If no amplifier is attached then its position (third character) contains an asterisk (*).
On the *IDN? response the 4th comma separated value (firmware rev)
If the 2nd and 3rd characters in the firmware version are "EP"
then it is a 5700A/EP unit (upgraded 5700A to performance of a 5720A).
So Example 2 above is an EP unit.