Next Advance SP1800 - Manual (Page 40)

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SP1600/1800 Programmable Syringe Pump
Publication #1200-02 35 9/15/04
9.2.2 RS-232 Protocol: Basic Mode
Command syntax (to pump):
=>
Response syntax (from pump):
=>
In the “Basic” communications mode, a master-slave protocol is used, whereby the pump will only
transmit in response to a received command.
When the pump receives the , will automatically be stripped
of all space and control characters, and all text will be converted to upper case. This simplifies
communications with the pump when commands are being manually typed in from a generic terminal
emulator.
To return the pump to Basic mode when in the Safe mode, send the following packet to the pump:
(0x2) ( 0x8) SAF0 (0x55) (0x43) (0x3)
9.2.3 RS-232 Protocol: Safe Mode
Command syntax (to pump):
=>
Response syntax (from pump):
=>
Safe mode uses a more structured protocol. including detection of corrupted communications,
communications time outs, and auto-alarm responses. Safe mode is enabled using the ‘SAF’ command
whose parameter setting is stored in the non-volatile memory.
Safe mode uses a modified master-slave protocol, whereby the pump transmits in response to a received
command. But, the pump also automatically transmits a status packet when an alarm condition occurs.
Corrupted communications is detected using the 16 bit CCITT CRC algorithm computed over
. Packets transmitted and received include the CRC within the packets.
The parameter sent with the “SAF” command is the communications time out. This time out, in seconds,
is the time between the reception by the pump of consecutive valid communications packets. Each time a
valid communications packet is received, the time out is reset. If the time out elapses, a pump alarm will
occur, stopping the pump and the Pumping Program. The pump will display , and the buzzer
will sound, if alarms are enabled, alerting the user. The communications time out timer will not restart
until the next reception of a valid packet.
In addition, there is a 0.5 second packet inter-byte time out. While receiving a communications packet,
and before its complete reception, if a delay of 0.5 seconds occurs between bytes, the incomplete packet
will be discarded.
With the Auto-Alarm feature, whenever a pump alarm occurs, such as a pump stall, a response packet
with the alarm status information will automatically be transmitted.
Until the Safe Mode is disabled, each time power is applied to the pump, the pump defaults to the Safe
mode of communications, but the communications time out timer will not be enabled until the first
reception of a valid packet.
Although the communications time out timer is not enabled, the Auto-Alarm feature will be enabled.
Therefore, the pump will be in an Auto-Alarm only communications mode.
When power is applied to the pump, or if the system should reset, a system reset alarm occurs. The Auto-
Alarm feature, therefore, alerts the host computer that a pump reset has occurred.
Also, when the user changes the baud rate, the communications time out timer is disabled until the next
valid communications packet.