No Communication (Standard Serial Interface) - Intermec EasyCoder 501 Service Manual

26.2 Single Function
Failure, cont.
Intermec EasyCoder 501 – Service Manual Ed. 7
No communication (general), cont.
• Often the best way is to enter the Setup Mode via the full
Test Mode described in Chapter 25.4. This action will tempo-
rarily set the parameters of the "uart1:" interface to their default
values and bypass any startup program, allowing you to check
or change the setup values both from the display and via the
serial communication channel "uart1:". In the Test Mode, you
could also read the current setup by printing Test Label #5.
• Make sure that the communication parameters for the printer,
like baudrate, parity control, stop bit protocol, communication
hardware straps, etc., and those of its host computer actually
match.
• In addition, verify that the communication port selected agrees
with the one stated in the Setup Mode.
• With the aid of an oscilloscope, or some kind of line analyser
("break-out box"), verify that the interface signals to and from
the CPU board are correct. The interface circuits could have
been damaged as a result of voltage transients from the inter-
face. Being socket-mounted, these circuits are easily replace-
able.
Repeated damage is, however, an indication of insuffi cient
cable screening, or the electrical environment being too noisy.

No communication (standard serial interface)

• See also above "No communication (general).
• Check that the jumper on connector P-202 of the CPU Board
is correctly inserted so as to give the desired selection between
RS-232, Current Loop, and RS-422, see Chapter 18.
• Check that jumper for DTR/RTS Select on P-200 is placed in
accordance with your cable and protocol.
• Verify that the supply voltages +5V are present.
• If the external device requires current supply from the printer
(+5V), a jumper must be fi tted on connector P-203. Typically,
this applies to the Intermec External Keyboard.
• If Current Loop is selected, verify that optional optocouplers
are mounted in sockets IC-205 and IC-206.
• If RS-422 is selected, verify that an optional RS-422 circuit is
mounted in socket IC-207 and that the communication straps
P-204 – P-207 are fi tted correctly, see Chapter 18.3.
• Using an oscilloscope, verify that all signals during receiving
and transmitting data have the appearance described in this
manual.
Chapter 26 Troubleshooting
205