Appendix A; Linkable Instrument Network; Start Up Sequence - Masterflex L/S 7523-60 Notice D'utilisation

APPENDIX A

PUMP DRIVE COMMUNICATION
SPECIFICATION
1.0 - LINKABLE INSTRUMENT
NETWORK
The Linkable Instrument Network is a serial
communication system consisting of a control
computer with one RS-232C port and one or more
satellite units. A satellite unit can be a pump drive
(7550-30, -50), mixer controller (50003-00, -05), or
any future product that conforms to the
communications protocol defined in this
description. This description describes all the
information needed to communicate with a pump
drive. Since much of this information applies to
other products, the term "satellite unit" will be used
as a generic term for all devices compatible with the
Linkable Instrument Network. The term "pump
drive" will be used when the information applies
only to MASTERFLEX Computerized Drives
(7550-30, -50).
Drives (7550-30, -50)
All communications between the control computer
and satellite units is based on a pseudo daisy-chain
principle. The transmission line of the control
computer will pass through the input and output
buffers in each of the satellite units. Each satellite
unit will have the ability to turn the buffers on and off
to block communications from other units below it in
the daisy-chain. The output of the control computer
would pass through each of the pump drives without
software assistance from the pump drive. All Pump
Drives in the daisy-chain must be powered up to
enable communications with all drives.
The receive line of the control computer will originate
in the transmitter of the last satellite in the chain. It
will also be double buffered through each satellite.
Each of the pump drives will have the ability to turn
off its input receive line and place its own transmitter
on the receive line to the control computer.
A third line, the Request To Send (RTS) will be a
similarly buffered line. Each satellite will have the
ability to set this line to signal the computer its
request to send.
The maximum number of satellites is limited to 25
by the Linkable Instrument Network software to
minimize communication time. However, up to 89
satellites could be controlled by a single RS-232C
port using custom software since satellite units can
be assigned any number from 01 to 89.
1.1 - SERIAL CONNECTIONS
The 7550 Digital PWM BLDC Drives communicate
with each other and a PC via a standard DB-9
modem cable (Cat. #22050-54). Older satellite units
have a dual 6 position modular phone jack labeled
"IN" and "OUT". Pin 1 on both jacks is located
towards the top of the drive. The control computer
will have a standard DB-25 plug as found on most
RS-232C connections. The DB-9 "AT" type
connector can also be used with the DB-9 to DB-25
adapter included with 7550-64 Computer to Pump
cable assembly.
"IN" JACK
Pin 1 - No connection
Pin 2 - Receive signal from the computer
Pin 3 - Transmit signal to the computer
Pin 4 - Ground
Pin 5 - Request to send (RTS) to the computer
Pin 6 - No connection
"OUT" JACK
Pin 1 - No connection
Pin 2 - Request to send (RTS) from the next satellite
Pin 3 - Ground
Pin 4 - Receive signal from the next satellite
Pin 5 - Transmit signal to the next satellite
Pin 6 - No connection
DB-25 PLUG ON CONTROL COMPUTER
Pin 2 - Transmitted data to satellite
Pin 3 - Received data from satellite
Pin 5 - Clear to send—RTS from satellite
Pin 7 - Ground
DB-9 PLUG "AT type" ON CONTROL
COMPUTER (DTE) AND SATELLITE
Pin 3 - Transmitted data to satellite
Pin 2 - Received data from satellite
Pin 8 - Clear to send—RTS from satellite
Pin 5 - Ground
DB-9 SOCKET ON SATELLITE (DCE)
Pin 3 - Receive signal from the computer
Pin 2 - Transmit signal to the computer
Pin 5 - Ground
Pin 8 - Request to send—(RTS) to the computer
The serial lines between units will be passed from
unit to unit by a hardware buffer on the input and
connecting it directly to the output driver through a
hardware gate. This way any output only sees one
input load. If power is turned off on any pump drive,
all drives below it in the daisy-chain cannot
communicate.
Figure A1 - Serial daisy-chain connections
11
1.2 - SERIAL DATA FORMAT
The serial data format is full duplex (simultaneously
transmit and receive), 1 start bit, 7 data bits, one odd
parity bit, and one stop bit at 4800 bits per second.
All data transmitted will consist of characters from
the standard ASCII character set.
Note: Odd parity is defined such that the sum of
the eight individual bits is an odd number
(1, 3, 5 or 7).
1.3 - SERIAL PROTOCOL
All transmissions originate or are requested by the
control computer (master). It may issue commands
directly and it may request that the satellites report.
When asked to report, the satellite would send the
data requested. Should a satellite require
communication with the computer, it has the ability
to operate the request to send (RTS) line. Upon
receiving the request, the computer would respond
via the serial line (section 1.11).

1.4 - START UP SEQUENCE

Normal start up would consist of turning on all the
satellite units first and then the control computer.
Each satellite will enable its receive and transmit
buffers and activate its RTS line. The control
computer would then send the enquire <ENQ>
command in response to the active RTS line. Upon
receiving the <ENQ> command, all satellites with
an active RTS line would disable its receive and
transmit buffers to the satellites below it in the
daisy-chain. Next the pump drives would respond
with one of the following strings depending on its
model number and version.
<STX>P?0<CR> = 600 RPM 7550 -30
<STX>P?2<CR> = 100 RPM 7550 -50
The control computer would only see the response
from the first satellite in the chain since
communications with the others is now blocked.
The control computer would then send back <STX>
Pnn<CR> with nn being a number starting with 01
for the first satellite and incrementing for each
satellite up to 25 maximum. If the pump drive
receives the data without errors it will perform the
following steps:
1. Deactivate its RTS line and enable the receive
buffers to the next satellite.
2. Send an <ACK> to the control computer.
3. Enable the transmit buffer from the next satellite
within 100 milliseconds after the last byte has
been sent.
4. Put a P and the satellite number received in the
first 3 positions on the satellite display.