Graseby 3000/500, Manual

Page: 223 / 231

Volumetric Infusion Pumps Graseby Medical L t d
3000/3100 and 500/505 Service Manual Issue 1(November 2001) 12 - 25
Response Time-outs and Error Processing
It shall be the host's responsibility to monitor pump responses, detect
a no response time-out and detect all other problems inherent in serial
communication. Error detection and recovery are the responsibility of
the host.
At 9600 baud, the typical command/response cycle time will be
approximately 1/2 to 1 second. This time is measured from the time
when the host starts to transmit a command until the time when the
pump completes the transmission of the response. At 300 baud, the
command/response cycle time may exceed 2 seconds. Three seconds is
the minimum recommended response frame time-out value.
Any framing, overrun, or overflow conditions will be ignored and the
problem will be sensed by means of the CRC check.
Problems that the pump encounters while executing commands will be
handled as outlined in the section 'Return Record Format'.
Summary of Handshaking and Hardware Connection
Handshake Signals
The host asserts RTS (Request to Send) prior to sending a command. If
ready, the pump shall respond by asserting CTS (Clear to Send) within
20 milliseconds of RTS active. The host may keep RTS asserted
indefinitely. Unless there is a fault, the pump shall keep CTS asserted
as long as RTS is asserted.
Hardware Connection
The Model 3000 uses a 9-pin sub D connector with female pins/male
housing. The pin definitions are defined below:
Pin # 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 max)
Note: This 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.