SRS Labs Lock-In Amplifier Status Byte Definition, Configuration Switches, SW1 GPIB Mode Switches

Status Byte Definition

Bit Meaning

0Magnitude too small to calculate phase

1Command Parameter is out-of-range

2No detectable reference input

3PLL is not locked to the reference

4Signal Overload

5Auto-offset failed: signal too large

6SRQ generated

7Unrecognized or illegal command

Configuration Switches

There are two banks of 8 switches, SW1 and SW2, located on the rear panel. SW1 sets the GPIB address and SW2 sets the RS232 parameters. The configuration switches are read continuously and any changes will be effective immediately.

SW1:GPIB Mode Switches

Bit	Example	Function
1 }	up	GPIB Address Switches
2 }	up	Address 0 to 30 allowed
3 }	up	'up' for bit = 1
4 }	down	'down' for bit = 0
5 }	up	(Most Significant Bit)
6	down	'down' to echo on RS232
		(normally 'up')
7	up	Not Used
8	up	Not Used

If the GPIB mode switches are set as shown in the example column above, then the lockin will be addressed as GPIB device #23, and all GPIB commands and data will be echoed over the RS232 for de-bugging purposes.

SW2:RS232 Mode Switches

Bit 1	Bit 2	Bit 3	Baud Rate
up	up	up	19200
down	up	up	9600
up	down	up	4800
down	down	up	2400
up	up	down	1200
down	up	down	600
up	down	down	300
Bit	Setting	Explanation
4	up	Odd parity
	down	Even parity
5	up	No parity
	down	Parity enabled
6	up	No echo (for computer)
	down	Echo mode (for terminal)
7	up	Two stop bits
	down	One stop bit
8		unused

Eight data bits are always sent, regardless of the parity setting. The most significant bit is always zero.

Example: Bit 1 'down' and all others 'up' for RS232 communication at 9600 baud, no parity, two stop bits, and no echo or prompts by the SR530.

8