DH Instruments MFC-CB, Руководство по эксплуатации и обслуживанию

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4. REMOTE OPERATION
Page 53
©2001~2007 DH Instruments, a Fluke Company
4.2.1.2 COM2
The MFC-CB COM2 RS232 interface is located on the rear panel. It is a 9-pin male
DB connector configured as a DTE device. Data is transmitted out of the MFC-CB
using pin 3 and is received on pin 2. This allows a standard pin to pin DB-9F to
DB-9M RS232 cable to be used to connect to a DCE slave. Handshaking is NOT
required or supported.
COM2 can be used to allow the host computer to communicate with another device
(e.g., a molbox or another MFC-CB) through the MFC-CB. This allows one host
COM port or IEEE-488 port to communicate with the MFC-CB and an additional
RS232 device. This configuration is frequently used to communicate with a molbox
and MFC-CB using only one computer COM port. Refer to the “PASSTHRU” “#”
remote command for details (see Section 4.3.5.2).
Table 7. COM2 DB-9M Pin Designation
PIN # FUNCTION DESCRIPTION
2 RxD This pin accepts serial data from another MFC-CB or
another device.
3 TxD This pin transmits serial data from the MFC-CB to another
MFC-CB or another device.
4 DTR Data Terminal Ready. Held at +5 Volts.
5 Grn This pin is the common return for the TxD and RxD signals.
IBM PC/XT DB-25F TO DB-9M
CONNECTIONS
IBM PC/XT DB-9F TO MFC-CB DB9M
CONNECTION
DB-25F DB-9M DB-9F DB-9M
2 3 3 3
3 2 2 2
7 5 5 5
4.2.2
IEEE-488 (GPIB)
The MFC-CB IEEE-488 interface is located on the rear panel. The physical and electrical
interface conforms to IEEE STD. 488.1-1987 Subset E2 and IEEE STD. 488.2-1992.
You should NOT attempt to communicate with the IEEE-488 interface while using the
COM1 interface. The IEEE-488 receive buffer is 250 bytes deep. The MFC-CB will hold
OFF release of the NRFD handshake line until it can service and empty the receive buffer.
This keeps the buffer from overflowing.
IEEE-488 commands must be terminated with a single line feed character along with the
assertion of the EOI line. All IEEE-488 responses from the MFC-CB are terminated with a
line feed character along with the assertion of the EOI line. Replies are held in a buffer until
the host computer retrieves them, so it is possible to have old replies in this buffer, while you
are expecting new replies from a just issued command. This is a very common problem
when you send a query form command and do not receive the reply, and then unexpectedly
receive this old reply instead of a new reply during the next query.