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

UBI EasyCoder 501 – Service Manual
26. TROUBLE SHOOTING, cont'd.
26.2
Single Function Failure,
cont'd.
No communication (general), cont'd.
Often the best way is to enter the Setup Mode via the full Test
Mode described in chapter 25.4. This action will temporarily 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 communica-
tion 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 hard-
ware 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 interface. Being
socket-mounted, these circuits are easily replaceable.
Repeated damage is, however, an indication of insufficient 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 fitted on connector P-203. Typically, this
applies to the UBI 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 RS422 circuit is
mounted in socket IC-207 and that the communication straps
P-204 – P-207 are fitted correctly, see chapter 18.3.
• Using an oscilloscope, verify that all signals during receiving and
transmitting data have the appearance described in this manual.
Continued!
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