Mesa 7I76 User manual

7I76 STEP/DIR PLUS I/O DAUGHTERCARD
V1.22

iii
Table of Contents
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
HARDWARE CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
GENERAL .................................................... 2
VIN POWER SOURCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
CABLE 5V POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
SETUP/OPERATE MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
ENCODER INPUT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
CONNECTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
7I76 CONNECTOR LOCATIONS AND DEFAULT JUMPER POSITIONS . . . . 3
HOST INTERFACE CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
TB2 STEP AND DIR CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
TB3 STEP/DIR, ENCODER AND RS-422 CONNECTOR . . . . . . . . . . . . . . . . . 6
TB4 SPINDLE CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
FIELD INPUT/OUTPUT CONNECTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
TB6 PINOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
TB5 PINOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
FIELD POWER CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
HOST INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
STEP/DIR INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
RS-422 INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
ENCODER INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
SPINDLE INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
SPINDLE ISOLATED OUTPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
STATUS LEDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

iv
Table of Contents
OPERATION
FIELDI/O .................................................... 13
FIELD AND VIN POWER SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
FIELD OUTPUT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
WHY SOURCING OUTPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
SHORT CIRCUIT PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
OVERTEMPERATURE PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . 13
MAXIMUM PER CHIP CURRENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
VOLTAGE CLAMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
FIELD INPUT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
WHY SINKING INPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
ANALOG INPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
FIELD VOLTAGE MONITORING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
WATCHDOG AND FAULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
FIELD I/O PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
NON-VOLATILE FIELD I/O PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . 16
OPERATE MODE BAUD RATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
WATCHDOG TIMEOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
RPD, WPD, AND UFLBP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SOFTWARE PROCESS DATA MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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Table of Contents
REFERENCE INFORMATION
SSLBP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
GENERAL .............................................. 19
REGISTER MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
PROCESS INTERFACE REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . 19
COMMAND REGISTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
COMMAND REGISTER WRITE IGNORE . . . . . . . . . . . . . . . . . . . . . . 20
DATA REGISTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LOCAL READ OPERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LOCAL WRITE OPERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LOCAL PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
NORMAL START . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
STOPALL .............................................. 24
STOP INDIVIDUAL CHANNELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DOIT .................................................. 24
PER CHANNEL INTERFACE DATA REGISTERS . . . . . . . . . . . . . . . . 25
PER CHANNEL CONTROL AND STATUS REGISTERS . . . . . . . . . . 25
REMOTE MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
INTERFACE AND CS REGISTER CONTENTS AT START . . . . . . . . . 25
CS REGISTER AFTER START . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
CS REGISTER AFTER DOIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
PROCESS DATA DISCOVERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
PROCESS TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
PROCESS DATA DESCRIPTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
PROCESS DATA DESCRIPTOR FIELDS . . . . . . . . . . . . . . . . . . . . . . 29
RECORD_TYPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
DATA_LENGTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
DATA_TYPE ............................................ 30
DATA_DIRECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
PARAMETER_MIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
PARAMETER_MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
UNIT_STRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
NAME_STRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
NUMERIC PROCESS DATA SCALING . . . . . . . . . . . . . . . . . . . . . . . . 31
MODE DESCRIPTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
MODE TYPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
PROCESS ELEMENT PACKING AND UNPACKING . . . . . . . . . . . . . 32
7I76 SPECIFIC PROCESS DATA EXAMPLE . . . . . . . . . . . . . . . . . . . 33
NORMAL MODE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
SETUP START . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
SETUP MODE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
REMOTE READ EXAMPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
REMOTE WRITE EXAMPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
DISCOVERY SEQUENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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Table of Contents
REFERENCE INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
LBP ........................................................ 41
LBP DATA READ/WRITEWCOMMAND . . . . . . . . . . . . . . . . . . . . . . . 41
EXAMPLE COMMANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
LOCAL LBP COMMANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
LOCAL LBP READ COMMANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
LOCAL LBP WRITE COMMANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
RPC COMMANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
EXAMPLE RPC COMMAND LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
SPECIAL RPCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
CRC................................................... 48
FRAMING .............................................. 48
SSERIAL REMOTE RPCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
DRAWINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

7I76 1
GENERAL
DESCRIPTION
The 7I76 is daughtercard/breakout board for use with MESA's 25 pin I/O FPGA
cards like the 5I25. The 7I76 is designed for interfacing up to 5 Axis of step &dir step
motor or servomotor drives andalso provides a spindle encoder interface, isolatedanalog
spindle speed control and 48 isolated I/O points for general purpose field I/O use.
All step and direction outputs are buffered 5V signals that can drive 24 mA. All
outputs support differential mode to reduce susceptibility to noise. An isolated analog
spindle voltage with direction and enable outputs is provided for spindle control as is a
single spindle encoder channel with TTL or differential inputs.
48 points of isolated field I/O are provided for general control use including limit
switch and control panel inputs, coolant enableand tool changer control outputs. Isolated
I/Oincludes32sinkinginputsand16sourcingoutputs.Inputscansense5Vto32Vsignals
and the outputs can switch 5V through 32V signals. Maximum output load is 300 mA.
Outputs are short circuit protected. Field I/O is powered by an isolated 8-32V field power
source.
One RS-422 interface is provided for I/O expansion via a serial I/O daughtercard.
All field wiring is terminated in pluggable 3.5 mm screw terminal blocks.

7I76 2
HARDWARE CONFIGURATION
GENERAL
Hardwaresetupjumperpositionsassumethatthe7I76cardisorientedinanupright
position, that is, with the host interface DB25 connector pointing towards the left.
VIN POWER SOURCE
The isolated field I/O on the 7I76 runs from a switching power supply that can be
powered by field power or a separate supply (VIN) with ground common with field power.
Normally the 7I76's VIN will be powered with field power. An on card jumper, W1 allows
VIN to be connected to field power. If you wish to use a single power supply for the 7I76s
field outputs and field logic power, W1 should be placed in the left hand position. This
connects field power to VIN. If you wish to use a separate supply for VIN, W1 Should be
placed in the right hand position.
CABLE 5V POWER
The 7I76 can get its 5V encoder, step/dir and serial interface power from the host
interface card if desired. W2 determines if the 7I76gets this 5V power from the host FPGA
card. If W2 is in the left hand position, host cable power is used. If W2 is in the right hand
position, 5V power must be supplied to the 7I76 via TB3. This option must be set to match
the cable power option of the host FPGA card. If the FPGA card supplies 5V, W2 must be
in the left hand position. If the FPGA card does not supply 5V, W2 must be in the right
hand position. Never apply external 5V power to the 7I76's TB3 connector when W2
is in the left hand position or you may damage the 7I76, FPGA card, PC, or
connecting cable.
SETUP/OPERATE MODE
The 7I76 can run in setup mode or operate mode. In setup mode, the serial
interface baud rate is fixed at 115.2K baud. In the operate mode, the baud rate is set to
2.5M baud (default). Setup mode enables a normal PC to communicate with the 7I76 for
setup purposes. W3 controls the setup/operate mode selection.T W3 must be in the
"operate" mode for normal operation.
W3 MODE BAUD RATE
LEFT Operate mode 2.5M baud (default, can be changed)
RIGHT Setup Mode 115.2K baud (fixed)
ENCODER INPUT MODE
The 7I76s high speed encoder input can be programmed for differential or single
ended mode operation. W4, W5 and W6 set the encoder input mode. When W4,W5,and
W6 are in the right hand position, theencoder input is mode is differential. When W4,W5,
and W6 are in the left hand position, the encoder input mode is single ended or "TTL".

7I76 3
CONNECTORS
7I76 CONNECTOR LOCATIONS AND DEFAULT JUMPER POSITIONS

7I76 4
CONNECTORS
P1 HOST INTERFACE CONNECTOR
P1 is the DB25F connector on the 7I76 that connects to the FPGA card. Actual pin
functions depend on FPGA configuration but signal directions must be observed.
DB25 PIN GPIO FUNCT DIR DB25 PIN GPIO FUNC DIR
1 IO0 DIR0 OUT 14 IO1 STEP0 OUT
2 IO2 DIR1 OUT 15 IO3 STEP1 OUT
3 IO4 DIR2 OUT 16 IO5 STEP2 OUT
4 IO6 DIR3 OUT 17 IO7 STEP3 OUT
5 IO8 DIR4 OUT 18 GND
6 IO9 STEP4 OUT 19 GND
7 IO10 SS0TX OUT 20 GND
8 IO11 SS0RX IN 21 GND
9 IO12 SS1TX OUT 22 GND or 5V
10 IO13 SS1RX IN 23 GND or 5V
11 IO14 ENCI IN 24 GND or 5V
12 IO15 ENCB IN 25 GND or 5V
13 IO16 ENCA IN
Notes
1. If jumper W2 is is the left hand position, pins 22 through 25 are 5V, if W2 is in the right
hand position, Pins 22 through 25 are GND.
2. GPIO pins are for first FPGA connector, next connector series begins at GPIO17
3. Signal directions are relativeto FPGA card, that is, an ‘OUT’ signal is anoutput from the
FPGA card that drives the 7I76. Conversely an ‘IN’ signal is a FPGA input that is driven
by the 7I76.

7I76 5
CONNECTORS
TB2 STEP AND DIR CONNECTOR
TB2 is the 7I76s main step and direction output connector. Both polarities of step
and direction signals are provided. Each channel onthe interface uses 6 pins. TB2 is a 3.5
MM pluggable terminal block with supplied removable screw terminal plugs.
TB2 CONNECTOR PINOUT
TB2 PIN SIGNAL TB2 PIN SIGNAL
1 GND 13 GND
2 STEP0- 14 STEP2-
3 STEP0+ 15 STEP2+
4 DIR0- 16 DIR2-
5 DIR0+ 17 DIR2+
6 +5VP 18 +5VP
7 GND 19 GND
8 STEP1- 20 STEP3-
9 STEP1+ 21 STEP3+
10 DIR1- 22 DIR3-
11 DIR1+ 23 DIR3+
12 +5VP 24 +5VP
Note: 5VP pins are PTC short circuit protected 5V output pins for field wiring.

7I76 6
CONNECTORS
TB3 STEP/DIR, ENCODER AND RS-422 CONNECTOR
TB3 has a mix of signals including step/dir channel 4, an encoder interface, a RS-
422 interface, and 5V power supply terminals TB3 is a 24 terminal 3.5 MM pluggable
terminal block with supplied removable screw terminal plugs.
TB3 CONNECTOR PINOUT
TB3 PIN SIGNAL TB3 PIN SIGNAL
1 GND 13 IDX+
2 STEP4- 14 IDX-
3 STEP4+ 15 GND
4 DIR4- 16 RS-422 RX+
5 DIR4+ 17 RS-422 RX-
6 +5VP 18 RS-422 TX+
7 ENCA+ 19 RS-422 TX-
8 ENCA- 20 +5VP
9 GND 21 +5V 5V supply power
10 ENCB+ 22 +5V 5V supply power
11 ENCB- 23 GND
12 +5VP 24 GND
Note: 5VP pins are PTC short circuit protected 5V output pins for field wiring.

7I76 7
CONNECTORS
TB4 SPINDLE CONNECTOR
TB4 is the spindle drive interface with isolated analog output and control signals for
a spindle interface.TB4 is a 8 terminal 3.5 MM pluggable terminal block with supplied
removable screw terminal plugs.
TB4 PINOUT
TB4 PIN SIGNAL
1 SPINDLE-
2 SPINDLE OUT
3 SPINDLE+
4 NC
5 SPINDLE ENA-
6 SPINDLE ENA+
7 SPINDLE DIR-
8 SPINDLE DIR+

7I76 8
CONNECTORS
FIELD INPUT/OUTPUT CONNECTORS
Terminal blocks TB6 andTB5are the 7I76s field input and output terminals. Inputs
0 through 15 and outputs 0 through 7 are terminated at TB6. Inputs 16 through 31 and
outputs 8 through 15 are terminated at TB5. TB6 andTB5 are 3.5 MM pluggable terminal
block with supplied removable screw terminal plugs. Pin one is at the bottom edge of the
7I76 card.
TB6 CONNECTOR PINOUT
TB6 PIN I/O TB6 PIN I/O
1 INPUT0 13 INPUT12
2 INPUT1 14 INPUT13
3 INPUT2 15 INPUT14
4 INPUT3 16 INPUT15
5 INPUT4 17 OUTPUT0
6 INPUT5 18 OUTPUT1
7 INPUT6 19 OUTPUT2
8 INPUT7 20 OUTPUT3
9 INPUT8 21 OUTPUT4
10 INPUT9 22 OUTPUT5
11 INPUT10 23 OUTPUT6
12 INPUT11 24 OUTPUT7

7I76 9
CONNECTORS
FIELD INPUT/OUTPUT CONNECTORS
TB5 CONNECTOR PINOUT
TB5 PIN OUTPUT TB5 PIN OUTPUT
1 INPUT16 13 INPUT28
2 INPUT17 14 INPUT29
3 INPUT18 15 INPUT30
4 INPUT19 16 INPUT31
5 INPUT20 17 OUTPUT8
6 INPUT21 18 OUTPUT9
7 INPUT22 19 OUTPUT10
8 INPUT23 20 OUTPUT11
9 INPUT24 21 OUTPUT12
10 INPUT25 22 OUTPUT13
11 INPUT26 23 OUTPUT14
12 INPUT27 24 OUTPUT15

7I76 10
CONNECTORS
FIELD POWER CONNECTOR
TB1 is the 7I76s field power connector. TB1 pinout is as follows:
TB1 PIN SIGNAL FUNCTION
1 VFIELD FIELD POWER 8-32V (Bottom pin)
2 VFIELD FIELD POWER 8-32V
3 VFIELD FIELD POWER 8-32V
4 VFIELD FIELD POWER 8-32V
5 VIN LOGIC POWER 8-32V
6 NC
7 NC
8 GROUND VIN, VFIELD, COMMON (Top pin)
Note: When W1 is in the default left hand position, VIN is connected to VFIELD, so only
VFIELD need be supplied to the 7I76 to power its field IO.

7I76 11
OPERATION
HOST INTERFACE
The 7I76 is intended to operate with a FPGA card with parallel port pinout like the
Mesa 5I25 or 6I25. The FPGA card supports the step/dir, encoder, and smart serial
interfaceusedbythefieldI/OandspindleinterfaceandexpansionRS-422port.TheFPGA
card can also supply 5V power to the 7I76.
STEP/DIR INTERFACE
The 7I76 provides five channels of step/dir interface with buffered 5V differential
signal pairs. Each differential pair consists of two complementary 5V outputs. The
differential signals allows reliable signal transmission in noisy environments and can
directly interface with RS-422 line receivers. Step motor drives with single ended inputs
connect to just one of the STEP and DIR signal outputs, that is either the STEP+/DIR+ or
STEP-/DIR- signals, with the unused signals left unconnected at the 7I76. The input
common signal on driveswith single ended inputs connects to the 7I76s GND or 5VP pins
depending on the drive type.
RS-422 INTERFACE
The 7I76 has one RS-422 interface available on TB3. This interface is intended for
I/O expansion with Mesa SSERIAL devices. The easiest way to make a cable for
interfacing the 7I76 to these devices is to take a standard CAT5 or CAT6 cable, cut it in
half, and wire the individual wires to the 7I76screwterminals. The following chart gives the
CAT5 to 7I76 screw terminal connections (EIA/TIA 568B colors shown):
TB3 PIN SIGNAL DIRECTION CAT5 PINS CAT5 568B COLOR
15 GND FROM 7I76 4,5 BLUE, BLUE / WHITE
16 RX+ TO 7I76 6 GREEN
17 RX- TO 7I76 3 GREEN / WHITE
18 TX+ FROM 7I76 2 ORANGE
19 TX- FROM 7I76 1 ORANGE / WHITE
20 +5V FROM7I76 7,8 BROWN/ WHITE,BROWN
Note: The6 pin terminal block requires the+5V (brown and brown/white) and ground(blue
and blue/white) pairs to be terminated in single screw terminal positions.

7I76 12
OPERATION
ENCODER INTERFACE
The 7I76 provide a one channel encoder interface with index. This is intended as
a spindle encoder but can be used for other purposes. The encoder input can be
programmedfordifferentialorsingleendedencoders. Theencoderinterfacealsoprovides
short circuit protected 5V power to the encoder. When used with single ended encoders,
the ENCA+, ENCB+ and IDX+ signals are wired to the encoder and the ENCA-,ENCB-,
and IDX- terminal left unconnected.
SPINDLE INTERFACE
The 7I76 provides one analog output for spindle control. The analog output is a
isolated potentiometer replacement type device. It functions like a potentiometer with
SPINDLE + being one end of the potentiometer, SPINDLEOUT being the wiper and
SPINDLE- being the other end. The voltage on SPINDLEOUT can be set to any voltage
between SPINDLE- and SPINDLE+. Polarity and voltage range must always be observed
for proper operation. The voltage supplied between SPINDLE+ and SPINDLE- must be
between 5VDC an 15VDC with SPINDLE + always being more positive than SPINDLE-.
Because the analog output is isolated, bipolar output is possible, for example with
SPINDLE+ connected to 5V and SPINDLE- connected to -5V, a+-5V analogoutput range
is created. In this case the spindle output must be offset so that 50% of full scale is output
when a 0V output is required. Note that if bipolar output is used, the output will be forced
to SPINDLE- at startup or when SPINENA is false.
SPINDLE ISOLATED OUTPUTS
The 7I76 provides 2 isolated outputs for use for spindle direction control, and
spindle enable. These outputs are OPTO coupler Darlington transistors. They are all
isolated from one another so can be used for pull up or pull-down individually. They will
switch a maximum of 50 mA at 0 to 100 VDC. The SPINENA output is special as it uses
the same signal that enables the analog output. When the analog output is enabled, the
SPINENA OPTO output is on.
STATUS LEDS
The 7I76 has two yellow status LEDs for power monitoring, CR1 and CR2. CR1 on
the top left side of the 7I76 monitors 5V power. CR2 on the top right side of the 7I76
monitors field power. Both LEDs must be illuminated for normal operation.

7I76 13
OPERATION
FIELD I/O
The 7I76 has a32 input, 16 output isolated field I/O system to support a wide range
of input and output devices. The isolated I/O is intended for low voltage DC control
systems (commonly 24VDC). Inputs are sinking type. That is they sense positive input
voltages relative to field ground. Output are sourcing type, that is they supply field power
to field ground referred loads.
VIN AND FIELD POWER SUPPLY
The 7I76 field I/O runs from field power supplies of 5 to 32 VDC. Field power
supplies the power to the 7I76 outputs and with the default settings, determines the 7I76
input thresholds.
VIN power runs the field I/O processor and normally is connected to field power.
VIN must be greater than 8V for proper operation. This means VIN must come from a
separate source if 5V field voltage is used. Power consumption is approximately 600 mW
or 25 mA at 24V. VIN power must be present for the 7I76 field I/O to be detected and
operate. Field voltages that are too high or too low will cause faults.
FIELD OUTPUT CHARACTERISTICS
The 7I76 field outputs are high side or sourcing type MOSFET drivers, that is they
source positive voltage to a ground referred load. For example with a standard 24V field
power, +24V connects to the 7I76s field power input (on TB1) and the outputs on TB5 and
TB6 now source +24V power to loads. All 7I76 loads will have one side returned to ground
or thenegative leadof the 24V supply. The 7I76s outputs can drive loads of up to 350mA.
WHY SOURCING OUTPUTS
Sourcing type outputs were chosen for the 7I76 because sourcing type field wiring
is less likely to cause inadvertent device actuation from the most likely type of field wiring
problem which is a short to ground.
SHORT CIRCUIT PROTECTION
The7I76soutputshaveshortcircuitprotectionandwillturnoff ifshortcircuit current
exceeds approximately 800 mA. The 7I76 firmware will detect this condition, disable the
affected output and indicate a fault.
OVERTEMPERATURE PROTECTION
The output driver chips detect over temperature conditions. If the 7I76 detects a
driver chip with a over temperature warning flag asserted, it will disable the affected chip
and indicate a fault.

7I76 14
OPERATION
FIELD OUTPUT CHARACTERISTICS
MAXIMUM PER CHIP CURRENT
Because of thermal limitations there is a maximum per driver chip total current of
1.4 amps continuous. Each driver chip connects to 8 sequential outputs. If this limit is
exceeded, the driver chip may go into thermal shutdown.
VOLTAGE CLAMPS
The output driver chips used on the 7I76 have built in Zener diode clamps to clamp
inductive turn-off (fly-back) spikes. This means that flyback diodes are not normally
required on small (less than 60 mA) inductive loads. If high current inductive loads are
switched or inductive loads are switched at high frequencies, they must have
flyback diodes to limit power dissipation in the 7I76's driver chips.
FIELD INPUT CHARACTERISTICS
The 7I76 field inputs have a nominal input resistance of 10K Ohms to field power
ground. 7I76 inputs sense positive input voltages above a preset threshold. For best
general purpose use, default input thresholdis 50% of the field power supply voltage with
10% hysteresis. That is with a 24V field voltage an input must be brought to 60% of 24V
= 14.4V to be sensed as high and then brought to 40% of 24V = 9.6V to be sensed as low.
These accurate thresholds and hysteresis allow high speed field signal detection while
maintaining excellent noise immunity.
WHY SINKING INPUTS
7I76 field inputs are of the sinking type. That is, external power must be applied to
the input to register as activated. This mode was chosen so that accidental grounding of
an input will not register as an activated input.
It is suggested that inputs like limit switches use normally closed switches with one
switch leg connected to field power and the other to the 7I76 input pin, so the normal
machine state (not at limits) is to have the inputs activated. This way, a open switch wire
or wire shorted to ground will cause a detectable machine fault.
ANALOG INPUTS
All field input pins are capable of reading the input voltage. These are not highly
accurate or high resolution but can be useful for things like potentiometer inputs. Input
resolution is 8 bitsand input full scale value is 36.3V. Accuracy is +-5%. Software process
data modes 1 and 2 allow reading the analog voltage on inputs 0 through 3, in addition to
the 32 digital bit inputs.
FIELD VOLTAGE MONITORING
The 7I76 monitors the field voltage and can send this information to the host in
some modes. If separate VIN is supplied to the 7I76, the 7I76 can report loss of field
voltage to the host.