IOtech Digital488OEM - Serial Poll Status Byte

Digital488 User’s Manual 7-17-01 Command Descriptions, 3-11
M8 will generate a Service Request when the Digital488 self-test fails. Refer to the Test command (T0)
description for details on self-tests.
M16 will generate a Service Request when the Digital488 has completed the execution of a set of
commands from the bus controller. This is used by the controller to assure the completion of a set of
commands before sending a subsequent set of commands.
Example:
CLEAR 718
reset the Digital488
OUTPUT 718;"M4X"
select SRQ on Bus error
OUTPUT 718;"F7X"
send an invalid bus command.
Note: ERROR and SRQ LEDs should illuminate
CLEAR 718
reset the Digital488
OUTPUT 718;"M1XM4X"
select SRQ on Bus error and SRQ on Service input.
OUTPUT 718;"M5X"
This has the same effect as the command above
where M1X plus M4X equals M5X.
Serial Poll Status Byte
The Serial Poll Output byte is sent upon receiving the serial poll command from the controller.
Refer to the SRQ description for details on how the Serial Poll byte is affected. Below is a description
of the significance of each bit in the Serial Poll byte.
Bit Location Significance (SRQ Bit Value if set to logic 1)
DIO1(LSB) 1 Service Input transition
DIO2 2 EDR input transition
DIO3 4 Bus error
DIO4 8 Test error
DIO5 16 Ready for more commands
DIO6 32 not assigned, always 0
DIO7 64 Service Request bit
DIO8 (MSB) 128 not assigned, always 0
Serial Poll Bit Description
DIO1
When enabled by the M1 command, DIO1 is set by a transition on the Service
Input line (active transition state determined by the Invert command (I64)).
DIO1 is cleared after the controller serial polls the Digital488.
DIO2
When enabled by the M2 command, DIO2 is set on an EDR transition
(active transition state determined by the Invert command (I32)).
DIO2 is cleared after the controller serial polls the Digital488.
DIO3
DIO3 is set when an invalid command is sent to the Digital488. The M4
command will enable a Service Request to occur then an invalid command
is received. The bit is cleared after the controller sends a Status command
(U0X) and reads the status string from the Digital488.
DIO4
The status of DIO4 is determined after the Test command (T0X) is sent to the
Digital488. If the self-test passes, the DIO4 bit will remain a zero.
If the self-test fails, DIO4 will be set to a logic 1.
The M8 command will cause a Service Request to be generated in addition
to DIO4 being set if the self-test fails. The DIO4 bit is cleared after the controller
sends a Status command (U0X) and reads the status string from the Digital488.