Sentry Sample Sentry II High Pressure, Installation, Operation & Maintenance Manual

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Sentry Sample Sentry II 41
Appendix A - MODBUS
Multiple Sample Sentry II controllers can communicate with a PC or control system via
MODBUS over a half duplex (2-wire), RS-485 network.
Figure 28 shows the MODBUS setup screen on the Sample Sentry II.
Figure 28. MODBUS Setup
M O D B U S S e t u p
►
A d d r e s s 1
B A U D 9 6 0 0 b p s
Each device on the network must be assigned a unique address. The address for each
Sample Sentry II can be in the range of 1 to 247. Use the
▲
and
▼
keys to change the
address setting. Use the ENTER key to toggle between the address setting and the BAUD
setting.
The controller is capable of operating using a BAUD rate of 19.2 kbps or 9600 bps. To
change the BAUD rate use the
▲
and
▼
keys.
The communications port uses 8 data bits, 1 stop bit, and no parity. The MODBUS mode is
RTU. These parameters cannot be changed.
Table 6. MODBUS Registers
Register Sample Sentry II Register R/W Format
30001 State Read Only INT 16
30002 Flow rate Read Only INT 16
30003 Inlet Pressure Read Only INT 16
30004 Outlet Pressure Read Only INT 16
30005 Inlet Temperature Read Only INT 16
30006 Outlet Temperature Read Only INT 16
30007 Cooling Out Temperature Read Only INT 16
30008 Sample Shutoff Valve (V1) Read Only INT 16
30009 Analyzer Valve (SV2) Read Only INT 16
30010 PRV Valve (# turns open) Read Only INT 16
30011 Elapsed Blowdown (seconds) Read Only INT 16
30012 / 40012 Sample Flow rate Set-point Read / Write INT 16
30013 / 40013 Blowdown Flow-rate Set-point Read / Write INT 16
30014 / 40014 Blowdown Duration Set-point (seconds) Read / Write INT 16
30015 / 40015 Startup Pressure Read / Write INT 16
30016 / 40016 Remote Start Read / Write INT 16