does anyone here have the rs232 wiring diagram for a Minimill. I will be recieving my 2002 minimill this Friday and would like to have the cable made by then. The cable will be 9 pin on pc side and 25 pin on minimill side I believe. any help would be greatly apprieciated.
If your cable only has 4 wires, you can also do this: CNC side (25-pin male) ----- PC side (9-pin female)
pin 1 ---- cable shield
pin 2 -------------------------- pin 2
pin 3 -------------------------- pin 3
pin 5 -------------------------- pin 7
pin 7 -------------------------- pin 5
pin 6 ---
pin 8 --- <-- jumper these 3 together on CNC side only
pin 20 --
Assuming that HAAS has not changed the wiring, then it is simple, and you need to decide if you want hardware or software handshake.
At the HAAS 25 pin end you need a male connector. And at the PC 9 pin end a female. At the HAAS end you can ignore pins 6, 8, and 20 because internally HAAS only jumpers these together. If you wanted to use this same cable on Fanuc, then you would need to jumper 6, 8, and 20 together, but not to anything else.
For software handshake:
At HAAS jumper 4 and 5 together, but to nothing else. This should not be necessary, but just in case you have problems and talk to someone at HAAS you can say 4 and 5 are jumpered.
At the PC 9 pin jumper pins 7 and 8. May not be necessary, but some software might require this.
Between HAAS and the PC connect pin 2 to 2, and pin 3 to 3, and HAAS pin 7 to PC pin 5. These are the data lines with 7 to 5 being common (ground). Pin 2 at HAAS is TxD, and 3 is Rxd.
Your cable capacitance which is determined by the cable and its length will determine your maximum baud rate up to the HAAS limit of 115.2 kbaud.
For hardware hand shake:
Same as software except remove jumper between between HAAS pin 4 and 5, and PC pin 7 and 8.
Connect HAAS pin 4 to PC pin 8, this is CNC RTS to PC CTS.
Connect PC pin 7 to HAAS pin 5, this is PC RTS to CNC CTS.
See my web site www.beta-a2.com for a discussion on isolation, noise, and ground paths. Also a wiring diagram for our E232 to HAAS is shown on the E232 PHOTO page. But be warned this is not the wiring to a PC. For PC wiring you have to interchange pins 2 and 3, and pins 7 and 8 at the PC end, and understand that the PC end connector is female instead of male.
Cat 5 is good low capacitance cable, means longer cable length for a given baud rate. Also the staggered twist pitch reduces cross magnetic coupling between transmit and receive.
At the HAAS end pin 1 connects to the machine chassis, the common lead of the PC power supply in HAAS, and the common to the serial UART. Pin 7 connects to pin 1 thru a 100 ohm resistor.
Pin 1 will be labeled shield ground, and pin 7 signal ground.
At your PC end pin 5 is connected to the PC chassis.
I will not argue for or against shielding on your CAT 5 cable. It is important that you use one twisted pair for pins 2 and 7 at HAAS and one of the other twisted pairs for pins 3 and 7 at HAAS. The two wires to pin 7 should be connected together at the PC to pin 5. I will suggest orange to HAAS pin 2 and thus orange/white to pin 7, and green to pin 3, and thus green/white to pin 7.
If you do not use a shield then probably connect HAAS pin 1 to 7. However, to minimize ground loop noise problems or electrical faults our I232 System can be of great value.
Cat 5e cable has more twists per foot than standard Cat 5. Cat 5e is a better cable for ethernet. However stranded wire cable would be a better choice if the cable is going to be moved around alot. Solid wire, like in ethernet cable, tends to break from being moved around.
This is the wiring I used on the Haas Mini mills.
The cable connector for Haas Mills
PC DB9 .............Haas Mill DB25
I do not recommend that you use CAT5 or CAT5e cable. These are UTP, or "Unshielded Twisted Pair" cables, and RS232 requires a shielded cable. The reason for this is simple:
RS232 signals are transmitted on one wire, and the voltage of that wire relative to "ground" is read by the receiving device. If there is noise on either the ground wire or the signal wire, you will get corrupted data.
Ethernet or RS422 signals are different. They use "differential" signals, where there are TWO wires for each signal. The only valid signal happens when one wire goes "high" and the other wire goes "low". A noise spike on the cable will place an identical spike on both wires, which is ignored by the receiving device. These type of signals are best transmited by twisted pairs, and the shield is not really needed.
The best wire we've found for RS232 is a low-capacitance double-shielded cable. You can buy 7 wire cable from Black Box Corporation at www.blackbox.com Look for the cable EMN-07A. You can get 500, 1000, or 2000 foot spools, or you can get custom lengths. The cable averages about $0.39 per foot.
A good generic wire would be 22 or 24 gauge stranded wire, with an overall foil or braided shield. Low-cap wire is good up to 500 feet, and generic wire is good up to about 100 feet.
Handshaking is a means to modulate the data flow from a sender to receiver to prevent buffer overflow.
It is possible to set handshake to none, but that is generally risky.
Hardware handshake a physical wire (signal path) separate from the data lines to signal when it is ok or not ok for the sender to send data. Requires 5 wires. The send or stop state is determined by the voltage level on the handshake line. So this would be defined as level sensitive. The hardware handshake could have been done as an edge triggered signal, but is not.
Software handshake uses the same serial communication lines as the data uses with two special control codes to signal stop (XOFF) and start (XON). These can best be described as edge triggering signals. This requires 3 wires.
Our I232 System provides electrical isolation to approximately 2000 volts at each end of the system, maximum baud rate of 115.2 kbaud, and at 4000 ft of interconnect cable. The electrical isolation eliminates ground loop noise common to HAAS machines with brushless servos. In the simplest form the I232 must operate in a software handshake mode. Higher cost to do hardware handshake. Also the I232 can be provided without bandwidth limiting for higher baud rates.
The I232 System is typically $200 plus interconnect cable, and shipping.