Physical Layout
The M20 standard interface board is 9 by 5 inches. It attaches to the controller board
through an edge connector. Refer to M20 Board Layout for mounting
hole locations. Mounting holes are designed to be used with stand-offs. See
M20 Schematics for I/O circuits.
Power Supply
Only a +5V power supply is required. The power supply voltage (s) are brought to the board
at header H2.
| PIN | DESCRIPTION | CURRENT | PIN | DESCRIPTION | CURRENT |
| 1 | N/C | 5 | logic +5V | 1.5A | |
| 2 | N/C | 6 | Feedrate CTR | 1-5K Ohm pot | |
| 3 | N/C | 7 | Feedrate HI | ||
| 4 | logic 0V (LCOMMON) | 8 | Feedrate LO |
The current usage listed is only for on-board requirements; off board requirements through the
motor and I/O headers can raise the current requirement.
Motor Driver Outputs
Step and Direction signals for four coordinated axes, a second X-axis, along with logic-common
(LCOMMON) , and +5V are located on Header H3. Outputs can be driven with 1004 inverting
drivers, or 1034 non-inverting drivers in locations U5 and U6.
The Motor Driver header (H3) is a twelve pin pluggable terminal strip.
| PIN | DESCRIPTION | PIN | DESCRIPTION |
| 1 | Step 0A | 2 | Dir 0A |
| 3 | Step 1 | 4 | Dir 1 |
| 5 | Step 2 | 6 | Dir 2 |
| 7 | Step 3 | 8 | Dir 3 |
| 9 | Step 0B | 10 | Dir 0B |
| 11 | +5V | 12 | LCOMMON |
The system builder must also make sure the pulse width is properly set for the motor drives. Use the command set_pulse_width to set the pulse setup time and pulse width of the output pulse train. Refer to your motor driver manual for the proper value. Refer to the Programmers Reference WinHelp File on our download page for a complete reference on the uCito programming language for our controllers.
WARNING: If the user wants to attain the maximum speed for any particular pulse width setting, the system builder must insure that the motor driver has no direction-line hold time requirement and that the driver steps off the leading edge of the step pulse.
WARNING: If the programmed pulse width is below the actual value needed for the motor driver, motion will appear to drift on the machine tool.
Two types of output wave forms are possible. The first has the direction setup and hold
periods centered about the leading edge of the step pulse. The second has the setup and
hold centered on the trailing edge. The first format is the STEP-S option.
The second is the STEP-H option.
Recommended Driver Connections
The quiescent state of these lines, with a 1034 output driver, is high. If a motor driver
has dual inputs for each signal input (step and direction), then the source voltage (5V) should
be connected to the positive (+) side of a motor driver signal input and the K520's output
lines should be connected to the negative (-) side. For example:
| Header/Pin | Description |
| H3 pin 1 | Motor 0 step (-) |
| H3 pin 2 | Motor 0 direction (-) |
| H3 pin 11 | Motor 0 step (+) |
| H3 pin 12 | Motor 0 direction (+) |
Output provisions for a second X-axis motor are provided on H3.9 and H3.10. Also see
pulse_enable in the MCIF Reference Manual.
Limit Inputs
Limit inputs are connected to H5 and H6 (if four axes are present) . The inputs are factory
configured for either +5V, +12V or +24V. To determine the board's configuration, check
R12-R15 and R22-R25.
| VOLTAGE | OHMS |
| 5V | 560 Ohms |
| 12V | 1.2K Ohms |
| 24V | 3.3K Ohms |
Current must flow through the inputs for motion to occur (limit switches are normally closed).
An open circuit will cause a limit detect.
| PIN | DESCRIPTION | PIN | DESCRIPTION |
| H5.1 | Limit Input 1 + | H5.2 | Limit Input 1 - |
| H5.3 | Limit Input 2 + | H5.4 | Limit Input 2 - |
| H5.5 | Limit Input 3 + | H5.6 | Limit Input 3 - |
| H5.7 | Limit Input 4 + | H5.8 | Limit Input 4 - |
| H5.9 | Limit Input 5 + | H5.10 | Limit Input 5 - |
| H5.11 | Limit Input 6 + | H5.12 | Limit Input 6 - |
| H6.1 | Limit Input 7 + | H6.2 | Limit Input 7 - |
| H6.3 | Limit Input 8 + | H6.4 | Limit Input 8 - |
Limit inputs 1 through 4 always generate over-travel exceptions and must be connected in all
cases. Jumpers J2-J5 configure the remaining limit inputs (5-8) for use as over-travel switches
(halts motion) or as general inputs (possibly homing switches).
| DESCRIPTION | JUMPER | OVER-TRAVEL | MISC / HOMING INPUT |
| Limit Input 5 | J5 | 1 - 2 | 2 - 3 |
| Limit Input 6 | J4 | 1 - 2 | 2 - 3 |
| Limit Input 7 | J3 | 1 - 2 | 2 - 3 |
| Limit Input 8 | J2 | 1 - 2 | 2 - 3 |
The E-STOP, PAUSE, and miscellaneous inputs also enter via optically isolating receivers, in which the current limiting resistors at set for +12V or +24V.
| PIN | DESCRIPTION | PIN | DESCRIPTION |
| H6.5 | Misc Input 1 + | H6.6 | Misc Input 1 - |
| H6.7 | Misc Input 2 + | H6.8 | Misc Input 2 - |
| H6.9 | Pause Input + | H6.10 | Pause Input - |
| H6.11 | E-Stop Input + | H6.12 | E-Stop Input - |
H7 is a dual row (even/odd) 16-pin ribbon cable header that can also be used for special input
connections. H7 has 5 non-isolated miscellaneous inputs. Miscellaneous inputs
1 and 2 are duplicates of the same inputs on header H6, but they are NOT isolated.
| PIN | DESCRIPTION | PIN | DESCRIPTION |
| H7.1 | LCOMMON (out) | H7.2 | +5V (out) |
| H7.11 | Misc Input 1 | H7.12 | Misc Input 2 |
| H7.13 | Misc Input 3 | H7.14 | Misc Input 4 |
| H7.15 | Misc Input 5 | H7.16 | N/C |
The following table shows the recommended limit switch line connections. The standard
X-axis is called the XA axis, when a second X-axis motor is present it is called the XB motor.
A single limit switch for the XB motor is provided for auto-squaring the table. The
Limit Input lines are abbreviated "LI".
| INPUT | LIMIT | INPUT | LIMIT |
| XA Low | LI1 | Z High | LI6 |
| XA High | LI2 | Z Low | LI5 |
| Y Low | LI3 | XB Low | LI7 (Misc In2 for multi-axis) |
| Y High | LI4 |
NOTE: The limit inputs lines are noise sensitive. On the machine tool the limit cables must not be run in the same conduit as (or along with) the cable going to the motors. Keep the limit cables away from any cable with high current or fast voltage swings; also, use shields for limit cables.
NOTE: To conform with the ANSI Robotics standard, the limit Input line, Pause Input, and E-stop Input must be a closed circuit for the controller to function. Open-circuits on any of these controls will cause the input line to be triggered.
For normally closed limit switch inputs and for most normally closed sensor-type inputs, a voltage difference across the inputs should be applied so that current flows through the diode. A break in current flow will activate the input. Normally closed proximity limit switches should be wired with the positive side going to the switched voltage (see R12 - R15 for voltage selection) and the negative side going to the positive input line on H5 or H6. A normally closed switch should be wired with one side going to the switched voltage (see R12 - R15 for voltage selection) and the other side to the positive side of the input line on H5 or H6. In these cases, the negative side of the input line should go to ground.
The "GO" line convention is to have no current flowing (normally open) so that a break in
the line does NOT trigger the event. The switched voltage (see
R12 - R15 for voltage selection) should be wired going to the positive side of the switch and
the negative side going to the positive input line on H6. The negative side of the input line
should go to ground.
| INPUT LINE | SWITCH TYPE | SWITCHED VOLTAGE |
| Limit | NC | 5, 12 or 24 volts (see R12 - R15 for voltage selection) |
| Go | NO | 5, 12 or 24 volts (see R12 - R15) |
| E-stop | NC | 5, 12 or 24 volts (see R12 - R15) |
| E-stop | None | Jumpered to 5, 12 or 24 volts (see R12 - R15) |
| Pause | NC | 5, 12 or 24 volts (see R12 - R15) |
| Pause | None | Jumpered to 5, 12 or 24 volts (see R12 - R15) |
Small capacitors are placed across the inputs to each isolator section to increase the noise
immunity. These capacitors (C17 - C28) are unlabeled on the
board and are just to the outside of each input isolation chip. Typical values would be
15mF.
The LED Array contains 10 red LED's used to indicate active input status. The first channel
is indicated by the LED segment towards inside of the board. These LED's indicate a break
in the input line. In other words, when a voltage difference (current flow) is not
present, that channel's LED illuminates. The individual LED's D2 (yellow), D3 (yellow),
and D4 (green) indicate Pause, E-Stop, and Power conditions, respectively.
The Green LED D4 illuminates when valid power is present.
Outputs
The M20 Interface Board supports 8 outputs, 4 of them are isolated. The isolated outputs
can be DC or AC mixed, depending on which type of module is inserted into the base. These
lines are fused for 3 Amps.
| Pin | Function | Pin | Function |
| 1 | Output line 1+ | 2 | Output line 1 - |
| 3 | Output line 2+ | 4 | Output line 2 - |
| 5 | Output line 3+ | 6 | Output line 3 - |
| 7 | Output line 4+ | 8 | Output line 4 - |
H7 is a dual row (even/odd) 16-pin ribbon cable header that can be used as an alternate output
header. H7 has 8 non-isolated outputs. Outputs 1 through 4 are duplicates of
the control signals for the outputs on header H4, but they are NOT isolated.
| Pin | Function | Pin | Function |
| 1 | LCOMMON (out) | +5V(out) | |
| 3 | Output line 1 | Output line 2 | |
| 5 | Output line 3 | Output line 4 | |
| 7 | Output line 5 | Output line 6 | |
| 9 | Output line 7 | Output line 8 |
Field Serviceable Components
The following table lists which components are socketed and can be changed in the field to fix
a particular failure.
| LOCATION(S) | IC TYPES | SIGNAL DESCRIPTION |
| U5--U6 | 74ALS1034 | Step Signal Drivers |
| U15--U20 | HCPL2630, 2631 | Input Isolated Receiver |
| ISO1-ISO4 | G4ODC5, G4OAC5 | Isolated Output Switches |