Schweitzer Engineering Laboratories SEL-2020, Instruction Manual, Page: 295 / 470

Date Code 20010518 Database 9-21
SEL-2020 Instruction Manual
Access by Bit
Individual bits within the database can also be accessed. Five bit access methods are available:
Bit Label
Port Number:Bit Label
Port Number:Region Label:Bit Label
Port Number:Address:Bit Number
Port Number:Region Label:Address Offset:Bit Number
The first two access methods are short hand notations for the third method. When only a bit
label is specified, the SEL-2020 searches the Global, then Local, and then TARGET regions for
the bit. When only a port number and bit label are specified, the SEL-2020 searches the Local,
then TARGET regions on the specified port for the bit.
The last two access methods use bit numbers. Bit numbers must be in the range 0 to 15 where 0
is the least-significant bit and 15 is the most-significant bit.
Bit access is primarily used within SEL
OGIC
Control Equations but can also be used within
SETM equations and by the VIEW and TOGGLE commands. Bits within archive regions may
not be used in SEL
OGIC
Control Equations nor by the TOGGLE command. They can still be
examined using the VIEW command. You can view the bit labels using the TAR, MAP region
BL, and VIEW region BL commands.
Consider accessing the local element CMD4 on Port 5 from the Port 5 settings. This bit can be
referenced the following ways:
CMD4 Bit Label
5:CMD4 Port Number:Bit Label
5:LOCAL:CMD4 Port Number:Region Label:Bit Label
5:0807h:4 Port Number:Address:Bit Number
5:LOCAL:7:4 Port Number:Region Label:Address Offset:Bit Number
Some other examples are:
ISSUE1=IN1 References Global IN1 element if the I/O board is installed;
otherwise references IN1 bit in TARGET region, if it exists.
VIEW 1:27L
or VIEW 1:TARGET:27L
View status of 27L bit on Port 1 within the TARGET region
(27L does not exist in Local region).
OUT2=5:TARGET:LOP Causes OUT2 to follow the state of the LOP element in Port 5’s
TARGET region.
OUT3=7:1234h:7 Causes OUT3 to follow the state of bit 7 (high bit of low byte)
of register 1234h within the Port 7 database.
X=9:D2:13h:Ah Causes X to follow the state of bit 10 within the 19th register of
Port 9’s D2 region.
Within a SEL
OGIC
Control Equation setting, if you reference a bit by address that does not exist,
the SEL-2020 will respond with a warning message, but it will accept the setting.