Red Lion C48C - Manual (Page 41)

Troubleshooting Serial Communications
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If problems are encountered when interfacing the C48C(s) and host device or
printer, the following check list can be used to help find a solution.
1. Check all wiring. Refer to the previous application example and use it as a
guide to check your serial communication wiring. Proper polarity of all
C48C(s) and other peripherals must be observed.
2. If the C48C is connected to a “host computer”, device or printer, check to
make sure that the computer or device is configured with the same
communication format as the C48C. The communication format the C48C
will accept is; 1 start bit, 7 or 8 data bits, no parity or 1 parity bit (odd or
even), and 1 stop bit.
3. Check the baud rate and parity in the Programming Menu SErSEt parameter,
and make sure all devices on the line are set to the same baud rate and parity.
4. Check the C48C’s unit address ( SErAdr ). If the Address command is not
used when transmitting a command to the C48C, the C48C’s address must be
set to 0. See Sending Commands & Data, page 26, for command structure.
5. If two-way communications are to be established between the C48C and a
computer, have the computer receive transmissions from the C48C first.
Activating a User Input, programmed for the print request function, will
initiate transmissions from the C48C.
6. When sending commands to the C48C, an asterisk * (2AH) must terminate
the command. Make sure a carriage return or line feed does not follow the
command terminator.
7. In multiple unit configurations, make sure each unit has a different address
other than zero. If a transmit value or print request command is issued, an
asterisk (*) must be sent before sending another transmission.
8. If all of the above has been done, try reversing the polarity of the transceiver
wires between the C48C(s) and the RS485 interface card. Some cards have
the polarity reversed.