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the power requirement of the instrument, but the advantages of a universal input supply
which exceeds power requirements and is correspondingly insensitive to large power
variation, often outweigh the small cost advantage of a smaller supply. The universal
input supply will operate from voltages over the range 100VAC to 240VAC 50Hz to
60Hz and has a modular AC cord which may be changed to match the power input and
socket type of local power.
Power switching
Operation of the power selector switch was described earlier. The instrument does not
support RS232 communications while on battery power. If you connect the unit in this
configuration the instrument will generate a power warning message, and you must
disconnect and reconnect the unit with external power selected.
Checking communications
Most programs have an initialization or check feature to make sure that the personal
computer and instrument can communicate. If this type of check is not automatic, asking
the program to display the unit id will check the connection. Each unit has a unique
identification. The personal computer can send a command to the unit, and if the
communications are working the unit will send back its unique identification. If the
program you are working with does not have this capability you can perform this check
yourself with a terminal emulator program set up for 9600 baud 1 stop 0 parity 8 data
bits. Simply type the keys “I” “D”, and Enter.
If the unit does not send back an ID you need to check the following items.
1.
Does the unit have power? What does the display say?
2.
Is the unit connected to the interface and the power supply?
3.
Is the modular cable connector selection switch pushed toward the cable you are
using?
4.
Is the 9-Pin D connector connected to the correct port on the computer?
5.
Did you tell the program or terminal emulator the correct port (COM1, COM2 ..)?
If the unit does not have power, but all of the connections are correct, pick up the
interface box and look into the slots on the side. You should see a (dim) green light
emitting diode. If you cannot see any green light, you may need to repair or replace the
interface box.
If you have power and, all the right connections, but no communications, try connecting
and disconnecting the modular connector at the unit and push and pull on the modular
connector at the interface. This will rub the contacts together and can remove contact
contamination.
