Voltage and Resistance Measurements
RTD 3 Wire
RTD 4 Wire and full Bridge strain measurements
10 Channels per module
Auxillary Alarm I/O
Programmable Memory types
Alarm Levels and Scaling Functions
The 912 modules provide 20 channels of voltage and current measurement at 17 bit resolution and 1uV integrity and is fitted with general purpose disconnectable screw terminals. It can be used to measure standard standard Platinum RTD's in 2, 3 and 4 wire configurations. The resistance mode can be used for thermisters and other resistive transducers.
The module can be programmed to integrate signals to be measured over one complete mains cycle (50 or 60Hz) allowing the 912 to reject large amounts of mains borne interference superimposed on microvolt signals. During a measurement the interface is continually monitored and should it exceed the dynamic range of the measurement made an error is reported (a higher range is selected in Autorange).
Measurements can be made continuously or under direct command from the host computer and can be returned in one of several formats most convenient for the supervisory software
Analogue modules support three digital outputs and an input. these can be used in combination to drive a local alarm indicator. Two alarm outputs can be set by any channel outside a high (first output) or low alarm limit (second output). High and low outputs can be programmed for each channel together with a threshold deadband to ensure single transitions to alarm state. The digital output level is suitable to drive small externally powered relays using an isolated supply . The third output is an isolated relay and can be used to drive an audio alarm. This alarm output can be 'Acknowledged' and cancelled by a contact closure connected to the digital. The output will switch again when any alarm channel error condition occurs.
Note: The two alarm outputs and the acknowledge inputs are not isolated from the RS485 communications port