Control specifications, Process alarms, Digital communications – West Control Solutions 8700+ User Manual
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Specifications
59305, Issue 7
– March 2014
Control Specifications
Automatic Tuning Types:
Pre-Tune, Self-Tune.
Proportional Bands:
0 (ON/OFF control), 0.5% to 999.9% of input span at 0.1%
increments. ON/OFF control not valid for VMD controllers.
Automatic Reset
(Integral Time Constant):
1s to 99min 59s and OFF.
Rate
(Derivative Time Constant):
0 (OFF) to 99 min 59 s.
Manual Reset
(Bias):
Added each control algorithm execution. Adjustable in the
range 0 to 100% of output power (single output) or -100% to
+100% of output power (dual output).
Not valid for VMD controllers.
Deadband/Overlap:
-20% to +20% of Proportional Band 1 + Proportional Band 2.
Not valid for VMD controllers
ON/OFF Differential:
0.1% to 10.0% of input span.
Motor Travel Time
5 seconds to 5 minutes
Minimum Motor On Time
0.0 seconds to (Motor Travel Time/10)
Auto/Manual Control:
User-
selectable with “bumpless” transfer into and out of
Manual Control.
Cycle Times:
Selectable from 0.5s to 512 seconds in binary steps.
Setpoint Range:
Limited by Setpoint Upper Limit and Setpoint Lower Limit.
Setpoint Maximum:
Limited by Setpoint and Scale Range Upper Limit.
Setpoint Minimum:
Limited by Scale Range Lower Limit and Setpoint.
Setpoint Ramp:
Ramp rate selectable 1 to 9999 LSD’s per hour and infinite.
Number displayed is decimal-point-aligned with display.
Process Alarms
Maximum Number of Alarms
(Controllers):
Two “soft” process alarms (high, low, deviation or band) plus
Loop Alarm.
Maximum Number of Alarms
(Indicators):
Five “soft” alarms (process high or low)
Combinatorial Alarms:
Logical OR or AND of alarms to any suitable output.
Digital Communications
Type:
Asynchronous Serial.
Protocols Supported:
Modbus RTU (all models) and ASCII (some models).
Physical Layer:
RS485.
Zone address range:
1 to 99 (ASCII), 1 to 255 (Modbus).
Bit rate:
1200, 2400, 4800, 9600 and 19200 bps.
Bits per character:
ASCII: 10
Modbus: 10 or 11 (depending on parity setting)
Stop bits:
1
Parity:
ASCII: Even (fixed).
Modbus: None, even or odd (selectable).
Isolation:
Reinforced safety isolation from inputs and outputs.