Gated Integrators and Boxcar Averagers SR245 — Computer interface module with GPIB and RS-232 · Eight analog I/O ports · 8-bit digital I/O port · Two TTL I/O ports · RS-232 and GPIB interfaces · 3500 point sample memory · Simple command structure SR245 Computer Interface The SR245 Computer Interface module is a powerful tool for data acquisition. It provides both an analog and a digital interface between your computer and your experiment. RS-232 and GPIB interfaces Both RS-232 and GPIB interfaces are standard features of the SR245. Simple commands make programming easy from a variety of high-level languages—all that’s necessary is the ability to send and receive ASCII strings. For example, sending “?5” instructs the module to measure the voltage on the 5th analog input BNC. Other commands allow you to record in the module’s 3500 point buffer memory, ramp an analog output at a specified rate (for gate scanning), or read the contents of a digital counter. Analog I/O The eight analog I/O channels can be designated through software as all inputs, all outputs, or as a combination of inputs and outputs. All channels have 13 bits of resolution over the ±10.24 VDC full-scale range, with 0.05 % accuracy. Digital I/O Two front-panel digital I/O bits are provided for use as counters or triggers and can be set or read by the computer. Additionally, an 8-bit input and an 8-bit output port are available (on an internal connector) for your own custom digital interfaces. Stanford Research Systems Computer interface module

Analog Ports Configuration Any number of the eight ports may be designated under program control as input ports, the rest default to output ports. Inputs 1 MΩ impedance ±10.24 VDC range (protected to 40 VDC) 13-bit resolution (2.5 mV) 0.5 % accuracy Input offset <2.5 mV Maximum A/D rate is 2 kHz Outputs <1 Ω impedance. Short circuit current limit is 20 mA. 13-bit resolution (2.5 mV) 0.5 % accuracy Output offset <2.5 mV Digital Ports Type Front-panel inputs Front-panel outputs Two front-panel I/O TTL bits, one 8-bit digital input port, one 8-bit latched digital output port Input impedances >100...