➄
Basic 6250 Features
65
Using your own
Thumbwheel
Module
As an alternative to Compumotor's TM8 Module, you can use your own thumbwheels. The 6250's
programming language allows direct input of BCD thumbwheel data via the programmable inputs.
Use the following steps to set up and read the thumbwheel interface. Refer to the 6000 Series
Software Reference Guide for descriptions of the commands used below.
Step
➀
Wire your thumbwheels according to the following schematic.
Sign
Bit
Thumbwheel
#1
Thumbwheel
#2
Thumbwheel
#3
Thumbwheel
#4
Thumbwheel
#5
Thumbwheel
#6
Thumbwheel
#7
Thumbwheel
#8
IN8 MSB
IN7
IN6
IN5 LSB
IN4 MSB
IN3
IN2
IN1 LSB
IN9 (sign)
OUT4
OUT3
OUT2
OUT1
I/O GND
MSD
LSD
6250
Step
➁
Set up the inputs and outputs for operation with thumbwheels. The data valid input will be an input
which the operator holds active to let the 6250 read the thumbwheels. This input is not necessary;
however, it is often used when interfacing with PLCs.
Command
Description
>
OUTPLC1,1-4,Ø,12
Configure PLC output set 1 as follows: outputs 1-4 are strobe
outputs, no output enable bit, 12 ms strobe time per digit read.
>
INPLC1,1-8,9
Configure PLC input set 1 as follows: inputs 1-8 are data
inputs, input 9 is a sign input, no data valid input.
>
INLVLØØØØØØØØØ
Inputs 1-9 configured active low
Step
➂
The thumbwheels are read sequentially by outputs, which strobe in two digits at a time. The sign bit
is optional. Set the thumbwheels to
+12345678
and type in the following commands:
Command
Description
>
VAR1=TW5
Request distance data from all 8 thumbwheel digits
>
VAR1
Displays the variable—
*VAR1=+Ø.12345678
. If you do not
receive the response shown, return to step 1 and retry.