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3-4 SR (Special Relay) Area
The SR area contains flags and control bits used for monitoring PC operation,
accessing clock pulses, and signalling errors. SR area word addresses range
from 236 through 299; bit addresses, from 23600 through 29915.
The SR areas is divided into two sections. The first section ends at SR 255 and
the second section begins at SR 256. When an SR area word is used as an oper-
and in an instruction, the operand mustn’t cross over this boundary. Basic
instructions that access bits in the SR Area 2 have longer execution times.
Area Range
SR Area 1 SR 23600 to SR 25507
SR Area 2 SR 25600 to SR 29915
The following table lists the functions of SR area flags and control bits. Most of
these bits are described in more detail following the table. Descriptions are in
order by bit number except that Link System bits are grouped together.
Unless otherwise stated, flags are OFF until the specified condition arises, when
they are turned ON. Restart bits are usually OFF, but when the user turns one
ON then OFF, the specified Link Unit will be restarted. Other control bits are OFF
until set by the user.
Not all SR words and bits are writeable by the user. Be sure to check the function
of a bit or word before attempting to use it in programming.
Word(s) Bit(s) Function
236
00 to 07 Node loop status output area for operating level 0 of SYSMAC NET Link System
08 to 15 Node loop status output area for operating level 1 of SYSMAC NET Link System
237
00 to 07 Completion code output area for operating level 0 following execution of
SEND(90)/RECV(98) for SYSMAC LINK/SYSMAC NET Link System or CMCR(––) for a PC
Card
08 to 15 Completion code output area for operating level 1 following execution of
SEND(90)/RECV(98) for SYSMAC LINK/SYSMAC NET Link System or CMCR(––) for a PC
Card
238 and 241 00 to 15 Data link status output area for operating level 0 of SYSMAC LINK or SYSMAC NET Link
System
242 and 245 00 to 15 Data link status output area for operating level 1 of SYSMAC LINK or SYSMAC NET Link
System
246 00 to 15 Not used
247 and 248
00 to 07 PC Link Unit Run Flags for Units 16 through 31 or data link status for operating level 1
08 to 15 PC Link Unit Error Flags for Units 16 through 31 or data link status for operating level 1
249 and 250
00 to 07 PC Link Unit Run Flags for Units 00 through 15 or data link status for operating level 0
08 to 15 PC Link Unit Error Flags for Units 00 through 15 or data link status for operating level 0
251
00 Remote I/O Error Read Bit
Writeable
01 to 02 Not used
Writeable
03 Remote I/O Error Flag
04 to 06 Slave Rack number and unit number of Remote I/O Unit, Optical I/O Unit, or I/O Terminal
with error
07 Not used
08 to 15 Master’s unit number and word allocated to Remote I/O Unit, Optical I/O Unit, or I/O Terminal
with error (Hexadecimal)
SR (Special Relay) Area Section 3-4