Red Lion TSC - Manual (Page 65)

Connecting To A Host Terminal
Six TSC units are used to control a process in a plant. The TSC units are
located at the proper location to optimize the process. A communication line is
run to an industrial computer located in the production office. The drawing
shows the line connection. Each TSC is programmed for a different address
and are all programmed for the same baud rate and parity as the computer (ex
9600 baud, parity even).
An application program is written to send and receive data from the units
using the proper commands.
TROUBLESHOOTING SERIAL COMMUNICATIONS
If problems are encountered when interfacing the TSC(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 examples and use them
as a guide to check your serial communication wiring. Proper polarity of all
units and other peripherals must be observed.
2. If the TSC is connected to a “host computer”, device or printer, check to
make sure that the computer or device is configured with the same baud rate
and communication format as the TSC. The communication format the
TSC will accept is; 1 start bit, 7 data bits, no parity or 1 parity bit (odd or
even), and 1 stop bit.
3. Check the TSC’s unit address. If the Address command is not used when
transmitting a command to the TSC, the TSC’s address must be set to 0. See
“Sending Commands & Data” section for command structure.
4. If two-way communications are to be established between the TSC and a
computer, have the computer receive transmissions from the TSC first.
Activating the User Input, programmed for the print request function, will
initiate transmissions from the TSC.
5. When sending commands to the TSC, an asterisk * (2Ah) must terminate the
command. After system power-up an asterisk must first be sent to clear the
TSC input buffer.
6. In multiple unit configurations, make sure each unit has a different address
other than zero.
7. If all of the above has been done, try reversing the polarity of the transceiver
wires between the TSC(s) and the RS-485 interface card. Some cards have
the polarity reversed.
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