Yokogawa DR240 - Manual (Page 8)

1-2 IM DR231-11E
1.1 Description of Functions
Status Byte Format
The format of status byte output in serial polling is as follows:
0 0 0
Upper-level byte Lower-level byte
Interrupt generated at the end of A/D conversion.
Interrupt generated at the time of syntax error.
SRQ
Interrupt generated when the internal timer is being operated
or hourly, daily and monthly reports are created.
Interrupt generated when the chart reaches it’s end.
Interrupt generated after storing data on media, or reading
data from media (with a floppy disk drive).
Interrupt generated when measurement release is generated
while computation is in progress (with computation
functions).
Bit 8: Not used. Always 0.
Bit 7: SRQ
This bit changes to 1 when any cause of the bits 1 to bit 6 has been generated and interrupts
the controller. After responding to serial polling, this bit is set to 0.
Bit 6 This bit changes to 1 when a measurement release is generated while the computation is in
progress; otherwise, it is 0. This bit is effective only with optional computation functions.
After responding to serial polling, this bit is set to 0.
Bit 5 This bit changes to 1 when the chart reaches its end.
Bit 4 This bit changes to 1 after storing data on media, or reading data from media; otherwise, it
is 0. After responding to serial polling, this bit is set to 0.
Bit 3 This bit changes to 1 when the internal timer is being operated or hourly, daily and monthly
reports are created. Whenever one of the internal timers 1 to 6 is being used or reports are
created, the bit changes to 1. After responding to serial polling, this bit is set to 0.
Bit 2: This bit changes to 1 when a syntax error occurs in a command and is normally 0.
If there is an error in a command description, this changes to 1. After responding to serial
polling, this bit is set to 0.
Bit 1: This bit changes to 1 at the end of an A/D conversion; otherwise, it is 0.
When the A/D conversion of measured data is terminated, this changes to 1. After responding
to serial polling, this bit is set to 0.
Status byte and serial polling
• In IM commands, the bit status that is to be made effective must be specified. The status of
unspecified bits does not change to 1.
• If a new cause is generated before reading out a status byte for which a cause has already been
generated, the existing cause remains in the status byte as is and the new cause is added. For
example, if bit 1 is in 1 state and bit 2 is newly changed to 1 before reading out the status byte,
both bit 1 and bit 2 become 1.
The initial value
The initial value is ‘ IM2 ’.