MGR10 A/B/C - Revision : I (for 7.0 software revision)
54
PC to send the next character.
When the microhmmeter detects receipt of a line terminator character, RTS is negated whilst the
command line buffer is read and validated. This is to prevent the PC sending further characters whilst a
command is being validated. Following validation, RTS is re-asserted to permit the next command to
be transmitted by the PC.
CTS is an input to the microhmmeter and controls the transmission of characters. If the PC asserts CTS
(low) then the microhmmeter will transmit the next character from the output buffer (if one is waiting).
If the PC negates CTS (high) then the microhmmeter will not transmit the character, but will wait until
CTS is re-asserted. TXD will remain in the mark (low) condition whilst CTS is negated. Note that
changing CTS during transmission of a character will not disrupt the transmission of that character.
If a 3-wire (TXD, RXD, GND) connection is to be used, connect RTS to CTS at the microhmmeter
end. But take care; sending characters too quickly to the microhmmeter could cause its receiver buffer
(4 characters) to overflow and subsequent characters may be lost. Always use a time delay between
transmitted characters, or better still, use the full 5-wire connection for reliable hardware handshaking
of each character.
It is recommended that Sefelec cable assembly (Pt. No. 100031) be used for connecting the
microhmmeter to a PC. This has the 5-wire connection and will maintain EMC integrity.
6.2.1.2 Front Panel Set-up
Press “MENU” on the front panel and select “Rem I/F”. On the next menu, select “RS-232”. A further
menu allows selection of Talk Only mode and Baud Rate.
If no RS-232 card is fitted the warning message “** OPTION NOT AVAILABLE **” is displayed.
Talk Only Mode
This mode is useful for sending results directly to a printer without the need for a PC.
Select “ON” to set the Talk Only mode. In this mode, the interface will ignore all incoming interface
commands, and the instrument will remain in LOCAL control mode. The result of each measurement is
sent to the interface output with the resolution as per the main display. If the Temperature
Compensation is selected, then the compensated resistance will be sent. See section 4.1 for output data
format.
Baud Rate
On selecting Baud Rate, the current setting is displayed. This defaults to 9600 following a RESET
operation and is the usual setting on shipment. If this is acceptable press “OK”.
