Chapter 576Using software, specify the trigger source for the D/A subsystem as an external, positivedigital (TTL) trigger or an external, negative digital (TTL) trigger.Note: If you configure the synchronization mode as slave, the Sync Bus connectoraccepts trigger and clock signals from the master; you cannot use the Ext Trig connectoron the slave module. Refer to page 79 for more information.• Sync Bus trigger – When multiple DT9847 Series modules (or multiple DT9847 Series andDT9837 Series or DT9838 modules) are connected together using the Sync Bus (RJ45)connector, you can use the Sync Bus trigger as the start trigger of the slave module bysetting the synchronization mode of module to Slave. In this configuration, any other starttrigger for the slave module is ignored. Refer to page 79 for more information on thisconfiguration.Data Format and TransferData from the host computer must use offset binary data encoding for analog output signals,where 00000000 represents the negative full-scale voltage, and FFFFFFFFh represents thepositive full-scale voltage. Using software, specify the data encoding as binary.Error ConditionsThe DT9847 Series modules report any underrun errors by sending an underrun event to theapplication. This event indicates that the data buffers are not being sent from the host to themodule fast enough, and the D/A converter ran out of data. To avoid this error, try one ormore of the following:• Reduce the clock rate of the analog output operation• Close any other applications that are running• Run the program on a faster computer
