Rockwell Automation 1771-SF1 SERVO INT MOD - Manual (Page 15)

Programming and Operation
Chapter 3
3Ć3
Table 3.A
DAC Input/Output
Sign Bit Input Bit Pattern Analog Output Voltage
0 111 1111 1111 Ć10.000V
0 111 1111 1110 Ć9.995V
0 111 1111 1100 Ć9.990V
0 000 0000 0011 Ć19.5mV
0 000 0000 0010 Ć14.6mV
0 000 0000 0001 Ć9.7mV
0 000 0000 0000 Ć4.9mV
1 111 1111 1111 0
1 111 1111 1110 +4.9mV
1 111 1111 1101 +9.7mV
1 111 1111 1100 +14.6mV
(1)
1 000 0000 0011 +9.985V
1 000 0000 0001 +9.990V
1 000 0000 0000
(2) (3)
+9.995V
(1) LowĆTRUE Bit Patterns (2)= MSBY (3) = LSBY
The 12 bit binary input to the DAC is transferred to two bytes using two
write instructions. The Most Significant BYte (MSBY) is eight bits long.
It can be loaded into memory location 600EH. DSEN Line 16 enables the
transfer. The Least Significant BYte (LSBY) can be loaded into memory
location 600DH. It contains data in the upper 4 bits. The lower 4 bits are
not used. DSEN line 15 enables the transfer. DAC data is reset at
power-up or by the data byte reset command (write location 600BH).
Bit 2 of the control byte is used to inhibit amplifier drive current to the
servo motor. Bit 3 is used to turn OFF the servo motor amplifier. They
are low = TRUE optically isolated TTL outputs.
Control Byte (Servo Motor
Amplifier Inhibit)