Sensoray 118 Manuel d'utilisateur télécharger pdf (Page 21)

Sensoray Model 118 Smart A/D™ Instruction Manual 19 Commands: Channel Configuration

6.2.2 SetFailMode

Establishes open sensor data values for all channels. The

second command byte contains eight flags, one for each

channel. Flags are mapped to channels as follows: bit 7

(most significant) to channel 7, bit 6 to channel 6, etc.

If a flag is set (logic 1) and the corresponding sensor is

open, the value 32767 will replace the sensor data. On the

other hand, if a flag is reset and the sensor is open, the

value -32768 will replace the sensor data.

This function is useful for triggering alarms when open

sensors are detected, and for forcing the desired system

response to fault conditions in closed-loop process

control applications.

Driver

// Set Open Sensor data values for all eight channels.

VOID SetFailMode( USHORT BasePort, UCHAR OpenFlags )

{

SendByte( CMD_SET_OPENFLAGS );

SendByte( OpenFlags );

}

Example

// A controller uses a thermocouple on channel 1 to monitor furnace

// temperature. If the thermocouple fails, the Smart A/D must indicate

// a high temperature on channel 1 to ensure that the controller turns off

// the furnace heater. This code segment sets up channel 1 to fail high

// and all other channels to fail low.

SetFailMode( MyBasePort, 0x02 ); // OpenFlags = (0,0,0,0,0,0,1,0)

Command: (80),(OpenFlags)

Response: None

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Sensoray 118 Manuel d'utilisateur Page 21