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Sample Sequencer
Computer Communications
Communication Protocol:
The following capabilities are available at the computer:
• Complete remote programming of alarms and times, but not station number.
• Remote on/off setting of sample points. This also resets alarms. If all samples are
turned off, Sequencer goes to "OFF" mode.
• Remote start/reset.
• Receive timing set values.
• Receive low and high alarm set values.
• Receive all current Analog mA values.
• Receive status:
Mode status
All alarms
Active input and output channels
Current Analog mA value
A low start bit, eight data bits and one high stop bit are used. A computer transmission should always
be preceded by at least two rubouts. 2400 baud rate is used. The most significant four bits of each
data byte is a designator as follows:
0001 nnnn Data
0011 nnnn Command
1000 nnnn Station numbers, Sample Sequencer
1111 1111 Rubout
Unused numbers are reserved for station numbers of other controllers.
Each station reads every valid byte sent by the computer or another station. The station number in 0
to 7 form is OR'd to 10000000B to compare with the communication bytes being sent, and when there
is a match, the sequencer takes the next byte as a command to perform some function for the central
computer. Each Sequencer is a "slave" and does not originate.
Commands to the Sample Sequencer:
0011 0000B Send 8 high alarm values
0011 0001B Send 8 low alarm values
0011 0010B Send CYCLE, DELAY, DWELL set times
0011 0011B Send CYCLE, DELAY, DWELL actual times
0011 0100B Send A and D values 1 to 4
0011 0101B Send A and D values 5 to 8
0011 0110B Send status
0011 1000B Receive 8 high alarm values
0011 1001B Receive 8 low alarm values
0011 1010B Receive CYCLE, DELAY, DWELL set times
0011 1011B Receive status
0011 1100B Start/reset function
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SENTRY Equipment Corp • P. O. Box 127•Oconomowoc, WI 53066 • 262/567-7256 • FAX: 262/567-4523
Web: www.sentry-equip.com • e-mail: sales@sentry-equip.com
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