Rockwell Automation T6200 Compressor Anti-Surge and Capacity Controller - Manual (Page 195)

Modbus Interface – RS-232/RS-485
B-5
Boolean tags may be defined in a remote register block. Such tags are packed into register’s least
significant bit first. A comma between Boolean tags will force the start of a new register. When
the register is written by the remote device, all of the Boolean tags will be updated. Conversely, if
any Boolean is modified, the whole register will be written.
The <scale> modifier provides for the automatic conversion of engineering unit scales between the
remote points and the local tag values. Scaled tags are real and all real tags are scaled. Without
scaling, remote register point default to integer values; with scaling, remote register points default
to real values.
Register points may be treated as signed or unsigned and fewer than sixteen significant bits may
be either left or right justified within the register. Signed (-) or unsigned (+) registers are
specified by the leading “-“ or “+” which introduces the <scale> modifier.
Register width and alignment is specified by the optional [“:”a[[“-“]a<bits>]] field. The number
of bits ranges from –15 to 16 or 32. A negative number of bits specifies left alignment.
When a non-zero number of bits is specified, the [h,al] values default to the range of the register
field so that, if they are not overridden, (H,aL] is the resulting conversion range; however H alone
specifies conversion scale factor. When <bits> is zero, [h,al] default to (1,0) so that the register is
treated as an integer. The [H,aL,ah,al] values default to (1,0,1,0) when not otherwise specified. If
[H [, L [, h[, l]]]] is not specified, then the default data type remains integer. When <bits> is 32,
two registers are joined; the first (lower numbered) register is the most significant half. The
engineering unit conversion is as follows:
EU H reg
= *
Equation 1 Scale Factor Conversion
EU H L
reg l
h l
L
= −
−
−
+
( ) *
Equation 2 Conversion to Engineering Units
Tags are defined in the usual way, with the exception that the sequence “/+” or “-“ turns on or off
access by the host rather than the single character (“+” or “-“) which is all that is required in other
contexts. Tags are not separated by commas, a Comma marks the end of a MODBUS master
polling block.
Example #1:
PORT 5 9600 E81 RS-232 MODBUS RTU SLAVE OFFSET 0;
UNIT 1
01
C1100 C1101 C1102
41
H1100 !CH110101 !CH110102 !CH110103, CH110201 CH110202
;
LOOP LP1;
END;
Example #2:
PORT 5 9600 N81 R2-232 MODBUS RTU MASTER RETRY 10/0.750 @3.5;
UNIT 23 RETRY 10 @3
01 ’COILS_23-01-32[32], 11 ’DI_23-01-32[32], 41 COUNT -0.01 SPEED_SP SPEED_PV +:16
100 SPEED_CMD
+:-12 1200,1000,0xFFF0,0x3330 TEMP;
END;
ACCESS SPEED_SP;
/* Allow operator to send a new speed from host. */
LOOP L1;
END;