Requested data is returned in the same format as with GPIB, but with a preced
-
ing 'R' and a terminating new line character. SRQs are available, and are output
as SRQ message 'S' followed by a terminating new line character. When the
SRQ message has been received, an "!SPL" command (equivalent to the GPIB
serial poll) can be issued. The power meter will respond with the serial poll data
message which is a single character preceded by 'P' and terminated by a new
line character.
A device clear message !DCL can be sent to clear the power meter input and
output message queues, and terminate any GPIB or serial actions pending.
At power on, factory reset, in response to the MODINIT command, and after the
INIT key in the modem menu is pressed, the following sequences will be output:
1. +++ath\r\r
2. at&h1&r2x4v1q0f1s0=1e0\r\r
There will be a delay between the two sequences.
These sequences will initialize an attached Hayes-compatible modem. This is the
only type of modem supported.
5-10
RS232 MODEM
SUPPORT
The ML2430A Series Power Meter can be operated remotely through a modem
connected to the rear panel serial connector (See Chapter 3, Connectors, for the
location of the serial connector) using the GPIB/RS232 command set. The menu
selection System|Rear panel|RS232|MODE must be set to EXT COMMS.
To initiate communications with the power meter from a remote computer, com
-
munications must be established between the two modems. Once this is done,
the modems become transparent to the user, and GPIB/RS232 commands can
be entered as if the power meter is connected directly to the remote computer.
The power meter can also be configured to automatically dial a specified number
if one or more predetermined error conditions are met.
When an instrument state change occurs that initiates an AUTODIAL sequence,
the power meter will send an escape sequence "+++" to the modem. It will then
output commands to determine if there is a modem connected and, if there is,
whether it is connected through to another modem. If a modem is found and it is
not connected to a remote modem, the power meter will dial the number speci
-
fied in the "phone number" field. When the connection to the remote computer is
established, the power meter will send the serial SRQ message.
When an autodial sequence is initiated, different sets of characters will be seen
on the remote PC depending on what is connected to the power meter serial
port.
5-6 ML2430A OM
RS232 MODEM SUPPORT PROCEDURES
NOTE
Serial interface remote
operation is not avail
-
able when the
ML2430A Series
Power Meter is operat
-
ing from the internal
battery.
NOTE
It is recommended that
there is only one serial
command ineach com
-
mand string.Terminate
each command with a
newline character.
