SRS Labs SR530, Lock-In Amplifier manual Q1 Q2 QX QY, T m ,n, U m ,n

If n is included, then v may be sent also. v is the offset value up to plus or minus full scale in units of volts. For example, to offset half of full scale on the 100 ∝ V sensitivity, v should be "50.0E-6" or an equivalent value. However, if the sensitivity is then changed to 200 ∝ V, the offset is now half of the new full scale or 100 ∝ V. When the sensitivity is changed, the offset is preserved as a constant fraction of full scale rather than as a voltage referred to the input. The expand function will, on the other hand, preserve the value of the offset as an input referred voltage. Once a value of v is sent, the offsets may be turned off and on without losing the offset values by using the O commands without the v parameter. Note that the X and Y offsets will affect the R output but the R offset does not affect the X or Y output.

P {v}

If v is absent, the P command returns the reference phase shift setting from -180 to +180 degrees. When v is included, the phase is set to the value of v up to ±999 degrees.

Q1

Q2

QX

QY

The Q commands return the output values in units of volts or degrees. For an input signal of 50

∝V on a full scale sensitivity of 100 ∝ V, a Q command will return the string "50.00E-6". "Q1" and "Q2" read the parameters being shown on the Channel 1 and Channel 2 output displays as selected with the S command. "QX" and "QY" read the X (RCOS Ø) and Y (RSIN Ø) BNC outputs.

R {n}

If n is included, the R command sets the reference input trigger mode. If n is absent, the trigger mode is returned.

nMode

0 ositive

1 Symmetric

2 Negative

S {n}

If n is included, the S command selects the parameters shown on the Channel 1 and 2 analog meters, output digital displays, and output BNC's. If n is absent, the displayed parameter is returned.

n	Channel 1	Channel 2
0	X	Y
1	X Offset	Y Offset

2	R	Ø
3	R Offset	Ø
4	X Noise	Y Noise
5	X5 (D/A)	X6 (D/A)

T m {,n}

The T command sets and reads the status of the time constants. If m is "1", the pre time constant is selected, if m is "2", the post time constant is selected. The parameter m is required. If n is included, the T command sets the selected time constant. If n is absent, the setting of the selected time constant is returned.

n	Pre Time Constant (m=1)
1	1	mS
2	3	mS
3	10	mS
4	30	mS
5	100	mS
6	300	mS
7	1	S
8	3	S
9	10	S
10	30	S
11	100	S

nPost Time Constant (m=2)

0 none

1	0.1	S
2	1	S

U m {,n}

The U command sets and reads the unit's calibration bytes. m is the address offset of the byte, 0-511. If n is absent, the value of the addressed calibration byte is returned. If n is included, the addressed calibration byte is set to the value of n, 0-255. The new value will be in effect until the power is turned off or a reset command is issued. Use of this command is not recommended.

V {n}

If n is included, the V command sets the GPIB SRQ (service request) mask to the value n (0- 255). If n is absent, the value of the SRQ mask is returned.

W {n}

The W command sets and reads the RS232 character wait interval. If n is included, the SR530 will wait nx4 mS between characters sent over the RS232 interface. This allows slow computer interfaces to keep up. n can range from 0 to 255. If n is absent, the wait value is returned. The wait interval is set to 6 on power-up.

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