You can connect TXB to the RS485 "+" terminal and TXA to the RS485 "-" terminal.
Next you need to setup either the PLC or the Baldor to talk at the same baud rate and format. The default on the PLC is 38,400, 8, 1, n. If the Baldor has a different baud rate you may want to change that to the PLC's standard baud rate and format. Otherwise you can use the PLC's SETBAUD command to change the PLC's baud rate and comm format to that of the Baldor.
For the PLC to send a string "v1000" (I hope you mean ASCII strings, not binary number), execute the following statement:
PRINT #3 "v1000";
We assume that there is no need to send "CR" character to terminate the string? Otherwise you should remove the semi-colon at the end of the statement to force it to send CR character.
What format is the 8 bit number that you will receive? Is it binary number? If so, use the:
X = INCOMM(3)
to read binary data from the RS485 port. You can poll it until X become non -1.