D-Series Syringe Pumps - Isco
D-Series Syringe Pumps - Isco
D-Series Syringe Pumps - Isco
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D <strong>Series</strong> <strong>Syringe</strong> <strong>Pumps</strong><br />
Section 6 Serial Interface<br />
There are three types of operation within the network: network<br />
controller, master, and slave. A computer typically serves as the<br />
network controller. It supervises all data flow on the network. It<br />
also polls each unit which initiates data transfer and commands.<br />
Note<br />
The network controller (typically a PC) should not be confused<br />
with the pump controller. The network controller is used in<br />
addition to the pump controller.<br />
The slave unit simply responds to commands accordingly. The D<br />
<strong>Series</strong> pump functions as a slave unit. These functions may be<br />
combined in one unit; i.e., a computer can function as both a<br />
network controller and a master.<br />
All data transfers are in a frame format. When the network controller<br />
polls an instrument, it will start to respond within 200 ms.<br />
If it does not reply, it will be polled again. If after three attempts<br />
at polling it does not reply, it will be dropped from the polling<br />
rotation. When the instrument does respond, the polling rotation<br />
does not advance until an error-free transfer has occurred.<br />
The frame format for data transfers from the network controller<br />
is as follows:<br />
destination\acknowledgement\message source<br />
\length\message\checksum\[CR]<br />
• The destination is the 1-digit unit identification<br />
number of the instrument to receive the message.<br />
• Acknowledgment is one character to indicate the<br />
success of the previous transmission. There are three<br />
possibilities: (1) E means error, resend the message<br />
immediately (E is sent by the network controller only.<br />
Other units signify errors by not replying; causing the<br />
controller to resend the message). (2) B means busy,<br />
resend message at next poll. (3) R signifies previous<br />
message was received.<br />
• Message source is the unit ID of the unit that originated<br />
the message. If there is no message, this location<br />
is a space (20H).<br />
• Length is the length of the message in 2 digit,<br />
hexadecimal format. Maximum length is 256, with 256<br />
being represented by a 00. This field is eliminated if<br />
there are no messages.<br />
• Message field is the area where the actual information<br />
is located. The maximum length is 256 characters long.<br />
• Checksum is also a 2 digit hexadecimal number. This<br />
number, when added to all the previous characters in<br />
the message (excluding control characters), will result in<br />
a sum. If there are no errors, the result of modulo 256<br />
division of this sum should be 0.<br />
6-6