Multiline Message Control Functions. The Acceptor Handshake, Source Handshake, Listener, and Talker functions are implemented by the interface circuits of the power supply and the controller and require no action by the user. The LSN or TLK indicators turn on when the power supply is addressed to listen or talk. (The talker function includes serial poll, see below).
Service Request. Service request is a uniline message that can be asserted by the power supply to interrupt the controller. Service request can be generated by a power supply fault condition. The operator defines which of eight power supply conditions are defined as faults. Enabling or disabling a condition from asserting service request does not affect the condition within the power supply, nor does it affect the
A service request can also be generated at power on (PON), depending on the setting of the
If the power supply fails self test at power on it will not respond to serial poll or any other commands on
The SRQ indicator turns on whenever the power supply is requesting service from the controller, and remains on until the controller conducts a serial poll. Serial poll resets the SRQ bit and turns off the SRQ indicator, regardless of whether the fault that caused service request continues to exist.
Serial Poll. In a serial poll the controller can poll each device on the bus, one at a time. The power supply responds by placing the contents of the
Parallel Poll. Parallel poll allows the controller to receive one bit of data from each of many or all instruments on the bus at the same time. In Agilent Technologies power supplies this bit corresponds to bit 6, the RQS bit, of the serial poll register. Because the controller can receive this bit from at least eight instruments at one time, the controller can determine quickly which of a number of instruments on the bus requested service. The controller can then query that instrument to determine the cause of the service request. Parallel poll does not reset the service request bit in the power supply. The power supply’s response to parallel poll can be configured remotely from the controller, or it can be configured locally.
Unless configured remotely, the power supply responds to a parallel poll with a "1" on one of the DIO lines (if requesting service), as determined by the setting of its address switches. Addresses 0 through 7 correspond to DIO lines 1 through 8 (decimal weight 20 through 27). If the address switches are set to 8 or higher, the power supply will not respond to a parallel poll unless the unit is configured remotely. The power supply can not return a "0" to indicate it was requesting service unless it has been configured remotely.
The power supply can be configured remotely to respond to a parallel poll with either a ’’1’’ or a ’’0’’ on one of the DIO lines if the unit is requesting service. Configuration statements with a decimal value of 0 through 7 will configure the unit to respond with a "0" on one of the DIO lines 1 through 8; decimal values of 8 through 15 configure the unit to respond with a "1" on one of DIO lines 1 through 8. By configuring the power supply remotely, the address switches may be set to any address from 0 through 30 without affecting the parallel poll response. The capability to configure either a "0" or "1" response allows the user to AND or OR two or more instruments on one DIO line.
