Graseby 3000/500, Manual

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1 2 — 7
G r a s e b y M e d i c a l L t d .
12
3 0 0 0 / 3 1 0 0 a n d 5 0 0 / 5 0 5 S e r v i c e M a n u a l
V o l u m e t r i c I n f u s i o n P u m p s
I s s u e A ( A p r i l 2 0 0 2 )
Terminator
The last character of any record transmitted by the host or pump is
an ASCII ">" (3E hex). This character is recognised as the end of a
record upon any occurrence, so it is not a valid character in the
Command parameter area.
Additional non-message characters are allowed following the record,
such as a line feed or carriage return. These characters are ignored
by the pump.
Error Processing
The pump aborts command processing if a checksum, parity, framing,
or format error occurs; no response is sent to the host. The pump
begins looking for a record header ("<") character again. It is the
host's responsibility to determine that there is no response and to
interpret this as an error in transmission.
Summary of hardware connection and handshaking
Hardware connection
The Graseby Medical Volumetric pump uses a 9-pin sub D connector
with female pins/male housing.
The pin configuration does not allow a standard 9 to 9 pin connector,
but requires reversing of pins 2 and 3 and pins 7 and 8 at one end of
the connector.
The table below shows the definition of the pins in the RS-232
connector:
Pin number Definition
1 No connection
2 Receive
3 Transmit
4 No connection
5 Signal ground
6 No connection
7 Clear to send (CTS)
8 Request to send (RTS)
9 +5V out (35 mA maximum)
Handshake signals
The host asserts RTS prior to sending a command. If ready, the pump
responds by asserting CTS within 20 milliseconds of RTS active. The
host may keep RTS asserted indefinitely. Unless there is a fault, the
pump keeps CTS asserted as long as RTS is asserted.
During a response, the host may slow down the pump
communications by negating RTS. The pump finishes transmitting the
character in progress, then waits until RTS goes active. If RTS
remains inactive for more than 1 minute, the pump aborts the
response message. When RTS is again active, the pump begins
looking for a record header.