LabVIEW drivers - Gynkotek M480 HPLC pump

Gynkotek M480 HPLC pump

The information provided by Gynkosoft (a GW-BASIC program) is a good starting point for creating a vi to control the Gynkotek M480 HPLC pump. The following text describes the required RS232 cable and transferprotocol.

Finding the right cable

For the connection between a PC and this HPLC pump a null-modem cable is required.
A standard null-modem cable may not work. A break-out-box (in this case an AMLAN 'DATALINKER') and a cable-checker (in this case a PALADIN TOOLS 'PC CABLE-CHECK') can be used to establish the proper cable layout.

BREAK-OUT-BOX

	SWITCH	PIN
TD	8	2
RD	7	3
TC	6	15
RC	5	17
RTS	4	4
CTS	3	5
DSR	2	6
DTR	1	20
GND		7

ALL SWITCHES OFF: NO CONNECTION

LEFT OFF RIGHT ON: LINES CROSSED

LEFT ON RIGHT OFF: LINES STRAIGHT

All lines can be straight lines. Crossing the DTR line is allowed.

CABLE-CHECKER

9 PINS D-SUB

SHIELD	6
1	7,8
2	3
3	2
4	6
5	5
6	4
7,8	1
8,7	1
9	-

Line 4 may be connected to line 6.

Establishing the right protocol

RS232 setting GYNKOTEK M480

• baudrate 9600
• 8 databits
• 1 stopbit
• no pariy

Commands, such as listed below, which can be placed between "", are allways followed by a carriage return (ASCII code #OD, r in LabVIEW) and a newline (ASCII code #0A, n in LabVIEW).

After sending a command wait at least 250 ms before reading the response from the Gynkotek pump.

The response allways starts with the command itself followed by a carriage return and sometimes by one or more values.

Here is a list of known commands:

* open connection

  Hallo

  wait 750 ms before reading the response on the "Hallo" (not just 'H") command.

  the response contains the type of your Gynkotek pump.

  it is good practice to first invoke the "E" command, in order to close and clear the
  connection.

* set flow to 500 µl

  F500

* set 'B' fraction of flow to 33%

  B33

  the A fraction (%) will change to 100 - 33 - C fraction

* set 'C' fraction of flow to 33%

  C33

  the A fraction (%) will change to 100 - B fraction - 33

* set upper pressure limit to 100 (bar)

  >100

* set lower pressure limit to 10 (bar)

  <10

* request system information

  S

  wait 1000 ms before reading the response from the Gynkotek pump.

  the response is quite lengthy and may look like this:

  Sr1300rn0000rn0200rn;001rn1900rn1900rn0500rn0000rn?>00rn90?0rnn
  1  2       3       4       5       6       7       8       9       10      11

  1	original command
  2	version
  3	?
  4	?
  5	total flow
  6	B fraction
  7	C fraction
  8	pressure
  9	?
  10	?
  11	?

  the response consists of some semi-hexadecimal values.

  for the analysis of the response use the following list to convert semi-hexadecimal
  to hexadecimal:

  character	hexadecimal	decimal
  in response	value		value

   :		 A		 10
   ;		 B		 11
   <		 C		 12
   =		 D		 13
   >		 E		 14
   ?		 F		 15

  this can be applied to the above response, e.g.:

  total flow	[5]	;001 reads as 01BO = 0*4096+ 1*256+11*16+ 0*1 = 432 (µl)
  B fraction	[6]	1900 reads as 0019 = 0*4096+ 0*256+ 1*16+ 9*1 = 25 (%)
  pressure	[8]	0500 reads as 0005 = 0*4096+ 0*256+ 0*16+ 5*1 = 5 (bar)

  note that in each word type value the first and second byte swap places.


* close connection

  E

  don't forget to read the response even if this command closes the connection.
  all other (single) letters of the alphabet have no command function.

Downloads

demonstration vi
This vi opens the serial connection, closes/opens the connection to the pump and sets all possible values. It reads back all possible process values, closes the connection to the pump and finaly closes the serial connection.
connect sub-vi
This sub-vi enables further conversation between PC and pump.
disconnect sub-vi
This sub-vi disables further conversation between PC and pump.
get setting sub-vi
This sub-vi retrieves the current readings of flow and pressure.
calculation sub-vi
This sub-vi converts the strange looking strings like >803 into decimal values like 1000.
set "B" fraction sub-vi
This sub-vi sets the B fraction (%) of the flow and changes the A fraction accordingly. There is no error-checking.
set "C" fraction sub-vi
This sub-vi sets the C fraction (%) of the flow and changes the A fraction accordingly. There is no error-checking.
set flow sub-vi
This sub-vi sets the flow (µl).
set lower limit sub-vi
This sub-vi sets the lower pressure limit (bar).
set upper limit sub-vi
This sub-vi sets the upper pressure limit (bar).

Remark

• All VIs have been made with LabVIEW 6.1