Keysight 53210A - Page 106

4 53210A Input Signal Conditioning
106 Keysight 53210A User’s Guide
Input Protection
The maximum input voltage (including any DC offset) allowed with 50Ω input
impedance is ±
5.125 Vp. If the input voltage exceeds
~
± 10.0 Vp, the input
protection relay opens - changing the input impedance to 1 M
Ω. (The display and
Impedance softkey will still indicate a 50
Ω setting however.)
With the relay open, the corresponding channel key flashes until the input voltage
is removed or reduced below the damage threshold and the key is pressed. This
sets the impedance back to 50
Ω.
To programmatically determine if the protection relay has been opened, the
command:
INPut[1]:PROTection?
queries the relay state (0 = relay closed, 1 = relay open). With the input voltage
removed or reduced below the damage threshold, the protection relay is reset
(closed) with the command:
INPut[1]:PROTection:CLEar
setting the input impedance back to 50Ω.
Voltage Overload Bit The opening of the input protection relay corresponds to
the ‘Voltage Overload’ bit (bit 0) being set in the counter’s Questionable Data
Register group. The bit in the Condition register is cleared by the
INPut:PROTection:CLEar command or by changing the input impedance to 1
M
Ω.. The bit in the Event register is cleared by reading the register. See Chapter 8,
"Instrument Status" for more information.