z/VM: CP Commands and Utilities Reference - z/VM - IBM

DEFINE CU / CNTLUNIT
Operands
150 z/VM: CP Commands and Utilities Reference
nnnn
is the number of the control unit that you are defining. The variable nnnn must
be a 1- to 4-digit hexadecimal number between X'0000' and X'FFFE'.
TYpe
is the control unit type. Valid types are:
Dci
tells CP that this control unit uses the directed-coupled interlock (DCI) protocol.
DCI protocol is a method of data transfer up to 1.5 megabytes per second. DCI
protocol requires the sender to raise a signal on the interface along with the
byte of data being transferred. The signal and data must be maintained until the
receiver acknowledges receipt of the data.
STREAM3
S tells CP that this control unit uses a method of data transfer up to 3 megabytes
per second. This protocol does not interlock data streaming between sender
and receiver. Once the data transfer begins, the sender does not wait for
acknowledgement from the receiver before sending the next byte of data. The
control unit determines the actual data transfer rate.
STREAM4.5
S4
tells CP that this control unit uses a method of data transfer up to 4.5
megabytes per second. This protocol does not interlock data streaming between
sender and receiver. Once the data transfer begins, the sender does not wait
for acknowledgement from the receiver before sending the next byte of data.
The control unit determines the actual data transfer rate.
TYPE_2
UNSHARED
tells CP that this control unit supports concurrent multiple I/O requests. This
means that this control unit is synonymous with a Type 2 control unit.
SHARED
TYPE_1
tells CP that this control unit only supports one I/O request at a time. This
means that this control unit is synonymous with a Type 1 control unit.
ESCON
tells CP that this control unit uses the Enterprise Systems Connection (ESCON)
channel to control unit I/O interface to transmit data through optical cables. Also
specify this operand for control units attached through direct-system-device
(DSD), emulated-I/O (EIO), FICON converter (FCV) or internal-system-device
(ISD) channel paths.
FICON_CTC
tells CP that the control unit is a channel-to-channel (CTC) adapter on a FICON
channel path. At least one of the two sides of a FICON CTC connection must
have a FICON CTC control unit defined. If a FICON CTC control unit is defined
on both sides (which is recommended), the two connected channels determine
which side acts as the control unit at any given time. For a FICON CTC
control-unit definition to be effective, the FICON CTC facility must be installed in
the host with the control-unit definition
* indicates that the correct TYpe will be chosen automatically. Automatic selection
applies to control units attached through DSD, EIO, CNC, CVC, CBY, CTC, FC,
FCP, FCV, IQD, or ISD channel paths.