Manual
CH. 12        MAN0924-01-EN 
February 8, 2010   Page 72 of 124   # 1018 
12.1.3 Resource Definitions 
System Registers
System Registers (%S and %SR) are used to store general RX-371 status information. This 
information is used internally, and is also available to the operator via the System Menu, using the 
RX-371 display and keypad. The System Registers are also available for User Screens and can be 
accessed by Ladder Code. 
%S Registers 
%S Registers are 1-bit memory locations containing system status information, which are 
implemented as shown in 
Table 12.2: 
Table 12.2- %S Registers 
Register Name  Description 
%S1 
FST_SCN 
On during the first scan after entering RUN mode 
%S2 
NET_OK  On if CsCAN Network is functioning properly 
%S3 
T_10MS  On for 5 mS; Off for 5 mS 
%S4 
T_100MS  On for 50 mS; Off for 50 mS 
%S5 
T_SEC  On for 500 mS; Off for 500 mS 
%S6 
IO_OK  On if SmartStack I/O is configured properly 
%S7 
ALW_ON Always On 
%S8 
ALW_OFF Always Off 
%S9 
PAUSING_SCN 
On during the last scan before Pause-N-Load 
%S10 
RESUMED_SCN 
On during the first scan before Pause-N-Load 
%S11 
IO_FORCED  On if one or more I/O points are currently being forced 
%S12 
IO_FORCING  On if I/O forcing is enabled 
%S13 
NET_IO_OK  On if Network I/O (SmartStix) is functioning properly 
%S16 
  Ethernet COM module is OK 
%SR Registers 
%SR Registers are 16-bit memory locations, containing system status information, implemented as 
shown in 
Table 12.3. 
Note: Where 2 %SRs are combined to make a 32-bit value, the lower numbered %SR is the low word, 
while the higher numbered %SR is the high word. 
Table 12.3- %SR Registers 
Register  Name  Description  Min Val  Max Val 
%SR1 
USER_SCR  Current User Screen Number  1  1023 
%SR2 
ALRM_SCR  Current Alarm Screen Number (0=none)  0  1023 
%SR3 
SYS_SCR  Current System Screen Number (0=none)  0  14 
%SR4 
SELF_TEST  Bit-Mapped Self-Test Result  0  65535 
%SR5 
CS_MODE  Control Station Mode (0=Idle, 1=Do I/O, 2=Run)  0  2 
%SR6 
SCAN_RATE  Average Scan Rate ( / 10)  -  1000 
%SR7 
MIN_RATE  Minimum Scan Rate ( / 10)  -  1000 
%SR8 
MAX_RATE  Maximum Scan Rate ( / 10)  -  1000 
%SR9-10 
EDIT_BUF  Data Field Edit Buffer  0  2
32
-1 
%SR11-12 
LADDER_SIZE  Ladder Code Size  2  256K 
%SR 13-16 
Reserved - - - 
%SR17-18 
IO_SIZE  I/O Configuration Table Size  16  127K 
%SR19-20 
NET_SIZE  Network Configuration Table Size  34  1K 
%SR21-22 
SD_SIZE  Security Data Table Size  -  - 
%SR23 
LADDER_CRC  Ladder Code CRC  0  65535 
%SR 24-25 
Reserved - - - 
%SR26 
IO_CRC I/O Configuration Table CRC  0  65535 
%SR27 
NET_CRC  Network Configuration Table CRC  0  65535 
%SR28 
SD_CRC  Security Data Table CRC  0  65535 
%SR29 
NET_ID  This Station’s Primary Network ID (CsCAN)  1  253 










