Operation
26
GA 12.137/2.02 - 05/2002
3.5 Interface description
The compressor unit satisfies EU Directives regulating
electromagnetic compatibility (EMC). To ensure that
compatibility is maintained, use shielded cables to
connect the Sub-D connectors. Connect the shielding to
the metal housings of the Sub-D plugs.
Before every change of operating mode (buttons /
REMOTE / RS 232) it is necessary to first switch off the
compressor unit and the cold head while in the "old” ope-
rating mode and then to switch on again in the "new”
operating mode. Failure to observe this rule may result
in undefined operating states; see Section 2.5, "Operati-
on via the interfaces.”
The interface is available from software version 2.0.
Format:
4800,1,8,N,1
- 4800 BAUD
- 1 start bit
- 8 data bits
- no parity
- 1 stop bit
Pin assignment at 9 pin sub D of COOLPAK:
- pin 2: TxD (output of COOLPAK to RxD input of PC)
- pin 3: RxD (input)
- pin 5: GND
Communication with COOLPAK
- No handshake is needed (no XON/XOFF).
- During communication the COOLPAK is always the
slave and the PC always the HOST.
- The host (PC) can send two types of messages, i. e.
commands and data requests.
- The format of these messages is always as follows:
Byte 1: STX (= 02h = controle-B; h = hexa deci-
male)
Bytes 2..4 Command or data request
Bytes 5..X Command or requested data
Byte X+1 CR (= Carriage Return = 0Dh)
- With the exception of the first and the last byte all bytes
are ASCII type (20h..7Fh).
- The maximum theoretical value for X is 126.
- In messages with more than one data value the indivi-
dual data are separated from each other by a forward
slash (“/” = 2Fh).
- All used letters are ASCII capitals.
- All used numbers are ASCII decimals.
- Messages with wrong formats are ignored (no respon-
se).
RS 232/485
Ground
RxD →
TxD (to RxD input of PC) ←
Fig. 17: Pin assignments on the interface connector
* The required counter plug is available e.g. from
Framatome Connectors International:
9-pole, solder version, female DE09S064T
Metallized housing, straight exit 8655 2179
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