Omega DAQP-208, 208H, 308 user manual Scan List Register

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4.4 Scan List Register

One entry to the scan list register contains a 16-bit word or two 8-bit bytes. It specifies the internal channel and gain selection in the high byte or MSB, and the external channel and gain selection in the low byte or LSB, in addition to other control and configuration settings. The external selections are used for expansion card channels (up to 128), while the internal selections are for channels on board the DAQP card. Expansion cards are not included as part of the DAQP series data acquisition system, however, they can be purchased separately from your vendor.

The number of entries in the scan list ranges from 1 to 2048. There are no dependencies implied among the entries of the scan list. The user may choose any valid gain combination for any channel, internal or external. Channels can be scanned in any order required, repeated or not, with the same or different gain for each entry.

The scan list must be flushed before programming to guarantee the integrity of each entry. There must be an even number of bytes programmed into the scan list, with the low byte sitting at an even offset followed by the high byte, otherwise the channel scan result will be unpredictable.

It is strongly recommended that the differential/single-ended control bit (bit 14, MSB) be programmed the same for all the entries in the scan list. Single-ended configuration should be selected if there are expansion cards connected to the DAQP card. The synchronous sample hold bit (bit 6, LSB) is reserved for expansion cards.

The first channel flag (bit 7, LSB) has to be set for the first (and ONLY the first) entry of the scan list. The DAQP card hardware relies on this bit to tell the end (or the start) of the scan. In normal operations, the DAQP card starts one scan when triggered, (software or TTL trigger in one-shot mode or sampling pulse triggers from the pacer clock in continuous mode). During the scan, each entry in the scan list will be processed until it finds the entry that has the first channel flag set to ‘1’. The hardware then stops scanning and waits for the next trigger. The scan will continue indefinitely if none of the list entries has the flag set to ‘1’. On the other hand, if more than one entry has the flag set to ‘1’, the scan list will then be chopped into pieces. Each piece will require a trigger to be scanned. Should the flag be set to ‘1’ on an entry other than the first, a “starting offset” will be introduced to the scan list. Channel scanning will start from the entry with the flag set to ‘1’, run through the list, turn around and end at the one before it. Although this may be useful for diagnosis or special applications, it is the abnormal way of setting the first channel flag and should be avoided unless absolutely necessary.

DAQP-208/208H/308 Users Manual

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Contents DAQP-208/208H/308 Type II Pcmcia Data Acquisition Adapter sWARRANTY/DISCLAIMER Servicing North America For immediate technical or application assistanceServicing Europe Page Page Table of Contents Page Daqp Series Card Output Connector List of Figures and TablesIntroduction Hardware Configuration and Initial Setup Page Software Installation Windows NT Page Data Acquisition Software and Drivers DAQPACL.SYS DAQPAEN.EXE Page Device = C\DAQPACL.SYS Device = C\DAQPACL.SYS b300,i5 Page Page Page Device = C\DAQPAEN.EXE S0,r Field Wiring GND DA0 DA1CP-DAQPA Cable Assembly GNDDaqp Series Card Cable Mapping UIO-37 Screw Terminal Block UIO-37 Terminal BlockDC/DC Power Supply Theory of OperationAnalog Input Multiplexer Programmable Gain Control AmplifierScan List Register Trigger Circuit A/D Converter and Data Fifo Interrupt and Status Digital I/OA/D State Machine FifoTimer/Counter 10 D/A CircuitPage O Registers Pcmcia InterfaceSreset Address Map Bit Page Data Fifo Threshold Setting LSB 1080 Select channel 0, gain 2, 1st entry Page Page Page Page Digital input bit External gain select, high bit All Output Flush scan list command High byte of the almost full threshold 15 2K option 18. D/A Data Port Bit Definition Bits Explanation 15-13 19. D/A Update Modes 20. Timer/Counter Modes Page Page Page Specifications TTL DAQP-208/208H/308 Version April 12