Specifications

4. REMOTE OPERATION

Table 20. COM2 DB-9M Pin Designation

PIN # FUNCTION DESCRIPTION

2 RxD This pin accepts serial data from another molbox RFM or another

device.

3 TxD This pin transmits serial data from the molbox RFM to another molbox

RFM 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 MOLBOX RFM 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 molbox RFM 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 molbox RFM 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 molbox RFM 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 gets them, so it is possible to have old replies in this buffer, while you

are expecting new replies from a just issued command.

4.3 COMMANDS

4.3.1 COMMAND SYNTAX

All molbox RFM commands are ASCII strings. The user must wait for the molbox RFM to

reply before sending another command. An exception to this is the use of any of the IEEE

STD. 488.2 Common Commands via the IEEE-488 interface (these common commands are

shown first, and always start with an asterisk, “*”). The common commands only generate a

reply if using the COM1 port or the query form of the common command is used (command

followed by a “?”).