1-13
GY-2120WD/WS
SCSI BUS SIGNAL LINES
The bus driver of GY-2120WD is differential type.
The bus driver of GY-2120WS is single ended type.
The data bus supports 16 bits.
SIGNAL LINE INFORMATION
BSY
Indicates that the SCSI bus is being used.
SEL
Initiator selects the target in selection phase and the target selects the initiator in reselection
phase.
RST
Requires to reset all the devices connected to the SCSI bus.
However, this signal is not turned on in GY-2120WD/WS.
C/D
Identifies information. (1: Control information* / 0: Data information.)
I/O
Determines the direction of transmission. (1: Initiator
→
Target / 0: Target
→
Initiator)
MSG
The target drives this signal. (1: Message information / 0: Command status data information.)
REQ
The target drives this signal. This signal is used for handshake of data transmission.
ACK
The initiator drives this signal. This signal is used for handshake of data transmission.
ATN
The initiator drives this signal. This signal indicates that a message is required by the initiator.
* : The control information is the command, status or message information.
1-4. Connector/Cable Information
Host computer
GY-2120WD/WS
Data bus (bit 0-15, Parity P-P1)
Busy (BSY)
Select (SEL)
Reset (RST)
Control/Data (C/D)
Input/Output (I/O)
Message (MSG)
Request (REQ)
Acknowledge (ACK)
Attention (ATN)
Summary of Contents for GY-2120WD
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