RS232 setup

RS232 connector pinouts

The PHC10-3 PLUS communicates with the CMM computer via the RS232 cable as shown in the table below:

Pin

Signal

1

Screen

2

Transmitted data (Tx) to CMM computer

3

Received data (Rx) from CMM computer

4

RTS (request to send) to CMM computer +12 V after initialisation routing completed

5

CTS (clear to send) from CMM computer

CMM computer disasserts CTS to halt PHC10-3 PLUS transmissions

Connect pin 5 to pin 20 if CTS is not output from CMM computer

7

Signal ground (common)

20

DTR (data terminal ready) to CMM computer signifies PHC10-3 PLUS power ON condition

Baud rate selection

The baud rate is set using switches 1 to 3 as shown in the table below:

Baud rateSwitch 1Switch 2Switch 3
300DOWNDOWNDOWN
600UPDOWNDOWN
1200DOWNUPDOWN
2400UPUPDOWN
4800DOWNDOWNUP
9600UPDOWNUP
19200DOWNUPUP

 

CAUTION: To implement any changes press the "reset" button on the rear rear panel. Failure to do so will be the changes do not take effect.

Protocol selection

The PHC10-3 PLUS has two switch-settable command sets (basic command set and extended command set) offering different protocol options. The command set selection is made using switch 9 on the rear panel.

Switch

Position

Selection

9

UP

Extended command set mode (recs)

9

DOWN

Basic command set mode

Basic command set mode

In this mode the PHC10-3 PLUS is fully compatible with existing integration methods in terms of communications protocols, software command set and RS232 protocol options.

Basic command set protocol

Switch

Position

Selection

4

UP

2 stop bits

4

DOWN

1 stop bit

5

UP

CTS (clear to send) ON

5

DOWN

CTS (clear to send) OFF

6

UP

LF (line feed) ON

6

DOWN

LF (line feed) OFF

Data transmission format is as follows:

  • 1 start bit
  • 7 data bits
  • 1 parity bit (ignored on Rx: always 0 on Tx)
  • 1 or 2 stop bits (switch 4)

Protocols: PHC10-3 PLUS RTS is asserted before first transmission from the head and remains asserted. If switch 5 is UP, CTS must be asserted by the CMM computer to allow the head to transmit. If switch 6 is UP, the PHC10-3 will add an ASCII LF character to every transmitted message.

Extended command set mode

In this mode the PHC10-3 PLUS uses the Renishaw extended command set. It is completely different from and incompatible with the basic command set. The RS232 protocol is fixed with no user selectable options other than baud rate. The extended command set offers the following advantages over the basic command set:

  • Software control of the hand control unit (HCU2) functions such as jog and sweep
  • Software control of selected PICS (product interconnection system) functions such as probe damping, Probe Power OFF and LED OFF
  • Software control of selected probe functions (TP200 probe reset) Common communications protocol for products using the extended command set
  • As probing systems become increasingly sophisticated and offer a wider range of functions and control options, they will be incorporated into the new command structure, reducing integration times and costs for CMM manufacturers
  • The introduction of product identifiers and device numbers will enable control of multiple Renishaw interfaces in future implementations of the extended command set

Please contact Renishaw for further details of the extended command set. 

NOTE: The functions of switches 4, 5 and 6 will have no effect on the system when switch 9 is UP 

In extended command set mode, the data transmission and protocol formats are fixed in line with modem RS232 conventions. There are no user selectable options.

Data transmission format is as follows:

  • 1 start bit
  • 7 data bits
  • 1 even parity bit
  • 1 stop bit

Protocol:

  • PHC10-3 PLUS RTS is normally asserted. It is unasserted when the PHC10-3 PLUS is unable to receive further transmissions.
  • The PHC10-3 PLUS CTS must be asserted (by the CMM computer, or by linking DTR to CTS) to allow the PHC10-3 to transmit.

XON/XOFF:

  • The extended command set supports the use of XON/XOFF flow control by the CMM computer.
  • If the PHC10-3 PLUS receives an XOFF character, PHC10-3 PLUS transmissions will cease and be buffered until an XON character is received by the PHC10-3 PLUS or the output buffer overflows.
  • It is possible to continue transmissions to the PHC10-3 PLUS while it is in the XOFF state, although this is not recommended as it may cause overflow of the output buffer, resulting in lost responses.