HOST.pdf - 第48页

BM 122/ 123 /1 33/ 221/2 31 HOST COMPUTER SYSTEM 3. 6 Handli ng Communic ations Br eak E35HEC- 4A-201- A0 3.6- 1 The c able has been di sconnect ed whil e the equipm ent is wait i ng f or recepti on. W aiting f or r ec e…

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BM122/123/133/221/231
HOST COMPUTER SYSTEM
3.5 Wire-break Detection C2HB / R1HB
E35HEC-4A-121-A0
3.5-2
3.5.2 How to Check Errors
Host computer sends C2HB commands to the machine. (at Intervals of 30 s or more)
If the host computer receives an A2 command from the machine, communication via the port 1 is normal. If
it cannot receive the command, there is something wrong with the port.
If the host computer receives an R1HB command from the machine, communication via the port 2 is normal.
If it cannot receive the command, there is something wrong with the port.
When R command is disabled, R1HB command will not be returned.
If some trouble has been detected, it is necessary to make reconnection from the host computer side.
If an A4E00 command is returned instead of A2, command error may be the possible cause and there is
nothing wrong with the port.
3.5.3 Relation Between C2HB and Other C commands
Ex. 1
Another C5 command can be sent between a C2HB command and a response with an R1HB command.
Host computer system Equipment
C2HB (1)
(1) A2 (Data transfer end)
C5RE (1)
(1) A2 (Data transfer end)
(1) R1HB
(1) R1RE
(1) No data type (2) Data-attached type
Ex. 2
R commands are output regardless of the order of C commands received.
In case of C5RE, it may take time before an R1RE is output. In the meantime, a C2HB and an R1HB may be
completed.
Host computer system Equipment
C5RE (1)
(1) A2 (Data transfer end)
C2HB (1)
(1) A2 (Data transfer end)
(1) R1HB
(1) R1RE
(1) No data type (2) Data-attached type
=REMARKS=
If C5HB command is used when the R command buffer is full, the R commands will be removed in the order
they were stored.
BM122/123/133/221/231
HOST COMPUTER SYSTEM
3.6 Handling Communications Break
E35HEC-4A-201-A0
3.6-1
The cable has been disconnected while the
equipment is waiting for reception.
Waiting for
reception
Detect cable break before transmission and
disconnect
Waiting for
reception
Send a request for connection.
Request for connection
Clears the last connection automatically and
establishes a new connection for the
request.
Clears the last connection
New connection
Waiting for
reception
Remains waiting for reception because it
cannot detect disconnection by host
computer.
3.6. Handling Communications Break
E35HEC-4A-201-A0
Icons used in this section
: Equipment
: Host computer
3.6.1 Cable Disconnected while the Equipment is waiting for
Reception
BM122/123/133/221/231
HOST COMPUTER SYSTEM
3.6 Handling Communications Break
E35HEC-4A-201-A0
3.6-2
3.6.2 Cable Disconnected while the Host Computer is waiting
for Reception
The cable has been disconnected while the host
computer is waiting for reception.
Detects cable break before transmission
and disconnects automatically.
C2HB
Detect cable breaking by a C2HB
command.
Clear the last connection and send a
request for a new connection.
Establishes a new connection for the
request.
Waiting for
reception
Waiting for
reception
Waiting for
reception
Clears the last connection
New connection
Request for connection