H38 Absolute Explosion-Proof Encoder
Options and Tables Notes
Tel: 805-716-0322 /800-350-2727
Fax: 805-968-3154 / 800-960-2726
1461 Lawrence Dr, Thousand Oaks, CA 91320
www.beisensors.com
Serial Synchronous Interface (SSI)
SSI output provides effective synchronization in a closed-loop control system. A clock pulse train from
a controller is used to clock out sensor data: one bit of position data is transmitted to the controller per one clock pulse received by the sensor. The
use of a differential driver permits reliable transmission of data over long distances in environments that may be electrically noisy. The encoder utilizes
a clock signal, provided by the user interface, to time the data transmission. Receiving electronics must include an appropriate receiver as well as line
terminating resistors.
Features :
• Synchronous transmission • Transmission lengths to 1000 feet • Accepts clock rates from 100 KHz to 1.8 MHz
Data Transmission Sequence
1. Output driver of the encoder is a MAX 491 transceiver in transmit mode. The
recommended receiver is a MAX 491 transceiver in receive mode.
2. Controller provides a series of pulses (or differential pulse pairs) on the
CLOCK input lines.
3. On the first HIGH-to-LOW CLOCK transition, the encoder latches its data
at the current position and prepares to transmit.
4. Controller reads data on the falling edge of the next 15 clock cycles.
5. The first bit is a START bit and is always HIGH.
6. Next comes 13 data bits beginning with the most significant bit (MSB) and
ending with the parity bit. On 12 bit encoders, bit 13 is LOW. When parity is
not ordered, parity is LOW.
7. After the last CLOCK HIGH-to-LOW transition, a minimum of 40 microsec
-
onds must pass before the beginning of the next CLOCK series.
Interfacing Long Data Lines
Cable impedance can create a transmission delay, in effect, shifting the phase
relationship between the clock pulse and the data. If this phase shift exceeds
180°, then the wrong bit position will be sampled by the receiver. As a result,
the maximum allowable clock frequency is a function of the cable length. For
24 AWG, stranded, 3 pair cable (BEI part number 37048-003 or equivalent)
the group delay is 1.36ns/ft. The table below shows the maximum transmis
-
sion rate allowable as a function of cable length to ensure a phase shift of
less than 90°.
Ordering SSI :
HOW TO SPECIFY SSI OUTPUT IN THE ENCODER MODEL NUMBER:
Use the designation, S3 between the Code Format designation and the Connector
designation. Example: H25D-SS-12GC-S3-CW-SM18
Cable Length (ft) 50 100 200 300 500 1000
Max Freq (kHz) 1800 900 500 300 200 100
CLOCK, Maximum (kHz) = 92,000 / Cable Length (ft)CW
Output Code and Terminations (12 & 13 Bit)
12 Bit 13 Bit 12 Bit 13 Bit
MSB G
11
G
12
2
11
2
12
A
0
G
10
G
11
2
10
2
11
B
0
G
9
G
10
2
9
2
10
C0
G
8
G
9
2
8
2
9
D
0
G
7
G
8
2
7
2
8
A
1
G
6
G
7
2
6
2
7
B
1
G
5
G
6
2
5
2
6
C
1
G
4
G
5
2
4
2
5
D
1
G
3
G
4
2
3
2
4
A
2
G
2
G
3
2
2
2
3
B
2
G
1
G
2
2
1
2
2
C
2
LSB
12
G
0
G
1
2
0
2
1
D
2
LSB
13
G
0
2
0
A
3
0V (CIRCUIT COMMON)
1
B
3
DIRECTION OF COUNT
CASE GROUND
0V (CIRCUIT COMMON)
LATCH CONTROL
+V (SUPPLY VOLTAGE)
SHIELD DRAIN
WHT/BLK 1
WHT/BRN 2
WHT/RED 3
WHT/ORN 4
WHT/YEL 5
WHT/GRN 6
WHT/BLU 7
WHT/VIO 8
WHT/GRY 9
WHT 10
GRY/BLK 11
GRY/BRN 12
GRY/RED 13
GRY/ORN
ORN 18
GRN 16
BLK 15
YEL 17
RED 14
BARE
—
PARALLEL CODE TERMINATION TYPE
Gray
Code
Natural
Binary
Binary Coded
Decimal
Cable Term Board
H38 & H40
7230 Hollister Avenue | Goleta, CA 93117-2891 | Tel: (805) 968-0782 | Fax: (805) 968-3154
0539
CONNECTOR*
DATA+A
FUNCTION
YEL
CABLE
1
H40
TERM BOARD
DATA-H
WHT/YEL
7
CLOCK+ B
BLU
2
CLOCK- I
WHT/BLU
8
DIRECTION CONTROL C
ORN
3
ENABLE (OPTIONAL) J
WHT/ORN
9
SUPPLY VOLTAGE (+V)D
RED
4
CIRCUIT COMMON (0V) F
BLK
5
CASE GROUND G
GRN
6
Max. Frequency (KHz)
Cable Length (feet) 50
1800
100
900 500
200
300
300
200
500
100
1000
1212 13 14 15
START
BIT
MSB MSB-1 LSB12 LSB13
Parity
(Optional)
DATA+
CLOCK+
START
BIT
NEXT CLOCK
START OF
4
2
1
3
9
6
8
7
5
H38
1RB90
A
SPECIFICATION ADDENDUM, Serial Synchronous Interface SSI):
SSI output provides effective synchronization in a closed-loop control system. A clock
pulse train from a controller is used to shift out sensor data: one bit of position data is
transmitted to the controller per clock pulse received by the sensor. The use of a
differential driver permits reliable transmission of data over long distances in
environments that may be electrically noisy. The encoder utilizes a clock signal,
provided by the user interface, to time the data transmission. Receiving electronics must
include an appropriate receiver as well as line terminating resistors. An optional parity
bit is available to validate the transmitted data.
Features:
Synchronous transmission
RS422/485 compatible
Transmission lengths to 1000 feet
Accepts clock rates from 100 KHz to 1.8 MHz
Parity bit option is available
Data Transmission
Sequence:
1. Data from the encoder is sent with a MAX 491 transceiver in transmit mode. It is
recommended to use any RS-422/485 compatible receiver and provide a termination resistor
based on the RS-422/485 specification for your specific voltage and DATA line length.
2. The CLOCK signals are RS-422/485 compatible, differential TTL, with 180 Ohm termination
resistors internal to the encoder. A series of pulses from the controller, on the CLOCK
lines, advances the data.
3. On the first HIGH-to-LOW CLOCK transition, the encoder latches its data at the current
position and prepares to transmit. The DATA signal during this transition is a START bit,
which is always HIGH.
4. The encoder shifts data to the DATA line on each LOW-to-HIGH clock transition, beginning
with the MSB. The controller reads data on the HIGH-to-LOW transiton of the next 12 clock
cycles ending with the LSB. The parity bit (if parity option is specified) is clocked out on
the 14th clock cycle. When the parity option is used, the 13th bit output is a logic LOW on
a 12 bit Encoder or the LSB of a 13 bit Encoder.
5. Parity is even. The sum of all data bits and the parity bit is even.
6. After the last CLOCK LOW-to-HIGH transition, a minimum of 30 microseconds must pass
before the beginning of the next CLOCK series.
SPECIFICATION ADDENDUM
Serial Synchronous Interface (SSI)
REVISIONS
DESCRIPTION
DIMENSIONS ARE IN INCHES
APPLY AFTER FINISH
REMOVE BURRS AND BREAK ALL
SHARP EDGES .010 MAX
ALL DIA. TO BE WITHIN .010
ANGLES ± 0 30'
.XXX ±.005
.XX ±.01
TOLERANCES ON
63
UNLESS OTHERWISE SPECIFIED
APPR
ENGR
CHECKED
SCALE: NONE
SIZE
A
TITLE
1RB90
FSCM NO.
KRB
redrawn
04/06/05
DATE
LTR
924-02087-001
DWG NO.
SHEET: 1/2
APPRDATE
REV
A
924-02087-001
BEI
I N D U S T R I A L E N C O D E R D I V I S I O N
B E I T E C H N O L O G I E S , I N C.
BEI TECHNOLOGIES, INC. ANY REPRODUCTION, USE OR DISCLOSURE
THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF
OF THIS DOCUMENT WITHOUT WRIT TEN CONSENT OF
BEI TECHNOLOGIES, INC. IS EXPRESSLY PROHIBITED.
12-24VDC
(300mA MAX)
SIZE FSCM NO.
SCALE: NONE
DWG NO.
A
SHEET: 2/2
BEI
I N D U S T R I A L E N C O D E R D I V I S I O N
B E I T E C H N O L O G I E S , I N C.
924-02087-001
REV
Interfacing Long Data Lines:
Cable impedance creates a transmission delay, shifting the phase relationship between the clock pulse and the data. If this pulse shift exceeds 180 , then the wrong bit position will be sampled
by the receiver. The maximum allowable clock frequency, therefore, is a function of the cable
length. For 24 AWG, stranded, 3 pair cable (BEI part number 37048-003 or equivalent) the group
delay is 1.36nS/ft. The table below shows the maximum transmission rate allowable as a function
of cable length to ensure a phase shift of less than 90 .
CLOCK: Maximum (KHz) = 92,000/Cable Length (ft)
*Connector is a MS3102E18-1P, 10-pin connector on the encoder body and mates to an MS3106F18-1S connector or can be used with a standard cable/connector assembly, BEI P/N: 924-31186-18XX.
(XX = cable length in feet, ie. 10 = 10 feet)
Direction Control: Standard is CW for increasing count when viewed from the shaft end. Direction Control (Pin C) is normally HIGH (or N/C) and is pulled up internally to the positive supply voltage. To reverse the count direction,
Pin C must be pulled to LO (0V)
SSI Compatible Serial Code (S3):
20us Max
SSI Compatible Output with Parity Option Timing Diagram:
40us Min
30us Min
Encoder: H25D - SS - 12GC - S3 - SM18 - S
Example Model Number:
Specials:
-S = Parity Bit
To specify
SSI Output
AECO_500 4/13/05
30
40
SSI Timing
Direction of Count: Standard is CW increasing when viewed from
the shaft end. Pin 18 is normally HI (or N/C) and is pulled up inter-
nally to +V. To reverse the count direction, Pin 18 must be pulled
LO (COMMON ).
Latch control: Encoder outputs are active and provide continuous
parallel position information when Pin 17 is HI (or N/C). Pin 17
is pulled up internally to +V. When Pin 17 is LO (COMMON) the
encoder outputs are latched at the logic state that is present when
the latch is applied and will stay latched until Pin 17 is no longer
grounded.
See Doc. 01059-000 supplied with encoders
for Important Installation and Usage notes
summarized here.
Encoder Installation:
1. Environment: Hazardous Locations — UL
Complies with UL and cUL requirements;
CEN Shall comply with UL requirements plus
CENELAC/ATEX plus IECEx standards
2. WARNING: Open all circuits prior to connecting
this product to power and controller.
3. The installation must comply with NEC Class
2 circuits or with the regulations of the country
of use.
4. AWG 14 - 22 stranded wire stripped to .25
”
[6.3mm} is recommended.
5. Use agency approved 105° C minimum rated
cable/conductors housed within an approved
rigid conduit.
6. Conduit runs must have a sealing fitting certified
to 60079-0 Ex d IIB immediately at the entrance
to the device.
7. Tightly close terminal block access cover prior
to applying power.
8. For maximum bearing life, a flexible coupling
is recommended between encoder shaft and
driving shaft.
9. Thread sealant compound should be used for
1/2-14 fitting or cable gland to prevent ingress
of contamination.
During Use:
1. Keep terminal block access tightly secured
during use.
2. DO NOT loosen two 5/16
” set screws at
opposite face.
Maintenance and Service:
1. There are no user serviceable parts inside.
Encoder must be returned to factory for service.
2. WARNING: Open all circuits to this product
prior to opening access cover to disconnect
wires.
DATA + YEL 4
DATA- WHT/YEL 7
CLOCK+ BLU 5
CLOCK- WHT/BLU 8
DIR CONTROL ORN 6
CASE GROUND GRN 1
CIRCUIT COMMON BLK 2
+V SUPPLY VOLTAGE RED 3
SHIELD DRAIN BARE —
SSI Output Termination Table
Cable
Conn
Term.
Board
