Rockwell Automation 842SPA Serial to Parallel Adaptor - Manual (Page 2)

Publication 75008–134–01(E)
Document 910 990 103 490
August 2001
Printed in Germany
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Jumpers Needed
Connect the following three jumpers:
1. 842–SPA Ground (Terminal 1A) to Encoder Ground
(Terminal 1C)
2. 842–SPA Power (32C) to Encoder Power (32A)
3. 842–SPA Power (13C) to Parallel Output Driver Power
(31A)
Direction Control
When pin 12 of the encoder is connected to DC + (or left
floating), the 842A will count UP when the shaft is turned CW
when looking at the shaft. When pin 12 is connected to DC
return, the 842A will count UP when the shaft is turned in the
CCW direction when looking at the shaft.
Timing Diagrams
Below is an example of a timing diagram as viewed on an
oscilloscope. In this example, the 842A–31NB, a binary code
output with 4096 pulses per revolution and 4096 turns is
connected to an 842–SPA serial to parallel interface adaptor.
The 842–SPA generates an SSI clock burst of pulses. On the
positive slope of the start pulse, the 842A–31NB begins to
transmit its position data. In the example below, the
842A–31NB is returning 100000000011 (2051 Turns) and
001100000111 (775 position). After the data is sent, the output
remains in a low state for a short duration, then goes to a high
state in anticipation of the next SSI clock burst. The Error Bit
(bit 25) is normally zero. If there is a power interruption (e. g. –
low voltage) during data transmission, the Error Bit is set high.
0
0
1
1
TURNS SHAFT POSITION
0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0
...
...
BITS
VALUE
842–SPA
CLOCK +
842A
DATA +
1
12
11
10 8
13
14
15
16
17
4 2 3 6 5 7 9 18
19
20
21
22
23
1 24 1
25
ERROR BIT
SSI
Dimensions
Use the figure below to locate the mounting holes of the 842–CH.
5.5
(0.22) Dia.
30
(1.18)
15 (0.59)
131
(5.16)
121
(4.76)
45
(1.77)
24
(0.95)
76
(2.99)
"A" Terminals
"C" Terminals
...9 7 5 3 1 31
...8 6 4 2 32