Remote Processing RPC-150 - Manual (Page 9)

CHAPTER 2 SETUP AND OPERATION
RPC-150 Page 7
TROUBLESHOOTING
You pr obably tur ned to this section b ecause you could
not get the sign on message. If you are getting a sign on
message but can' t enter characters, then read section 5
below. The following ar e troubleshooting hints:
1. Check the pow er source . P ower is 5 ±0. 25 volts.
Make sure it is a clean 5 volt source. If it dips
intermittently to about 4.5 volts (due to switching
noise or ripple), the CP U may r ead an instruction
incorrectly and consequently ' crash' .
The power supply must be able to go from 0 to + 5
volts in under 100 ms. If it takes longer than this,
the card may come out of reset too soon and the
CPU will not operate correctly.
The best way to reset a card is to push the reset
button. When pow ering off then on, make sur e the
supply gets to at least 0.7 volts before turning on the
supply. The r eset circu it must dischar ge comp letely
for a clean reset. This is a problem on large, linear
supplies.
2. Check the COM 1 port. C OM1 is also known as J1.
Remove the connector from COM 1. Refer to the
outline drawing earlier in this chapter. Connect an
oscilloscope (preferred) or a voltmeter to pin 3
(Txd) and ground. Pin 3 should be -6 volts or more
negative. (Pin 1 is designated by the ### symbol on
the connector. Pin 3 is next to it, nearer the key
opening.) If you have -6 volts or more, press the
reset switch. If you have a scope attached, you
should see a bu rst of activity. If you have a volt
meter, you should see a change in voltage. Using a
Fluke 8060A set to measure AC, you should see a
momentary reading above 2 volts. Press reset
severa l times to m ake sure it captures it.
3. Install the cable and make sure the voltages and
output activity are still there. Output is from pin 3
on the VT C-10. Check to make su re som ething is
not shorting the output.
4. Check the serial pa ram eters on y our P C or termin al.
They should be set to:
19200 baud, no parity, 8 data bits, 1 stop
5. Many tim es a bad or wr ong serial cable can cau se
characters to get printed but you can' t send anything
to the card. M ake sure you are using a VTC -10
cable. This cable is wired per Chapter 4, SERIAL
CABLE PIN OUT.
If all of this fails, call technical support listed under
Chapter 1, TECHNICAL SUPPORT.