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Appendix A - MODBUS RTU Protocol
Notes:
1.
The Read function of the control register is not possible. To read the ASTAT-XT status, read the Logic_Status
(Actual parameter # 1).
2.
Bytes 2..8 of the control frame must be exactly as in the following example. Otherwise an error message is
returned.
3.
Hardwired Stop and Soft Stop inputs override the communication. To enable motor starting through
communication, terminals 4 and 5 (Stop & Soft stop) must be connected to the control voltage.
Example 5 - Control Register Write:
To start ASTAT-XT # 11, the host computer sends the following Query frame:
byte 1: Serial Link No.
($0B)
byte 2: Function
($10)
Bytes 2..8 must be as in this example!!!
byte 3: Starting Address High ($02)
byte 4: Starting Address Low ($F0)
byte 5: No. of Registers High ($00)
byte 6: No. of Registers Low ($01)
byte 7: Byte Count
($02)
byte 8: Data High
($5A)
byte 9: Data Low
($04)
Bit 2 is set, to start.
byte 10: CRC_Low
($XX)
byte 11: CRC_High
($XX)
The ASTAT-XT Normal response:
byte 1: Serial Link No.
($0B)
byte 2: Function
($10)
byte 3: Starting Address High ($02)
byte 4: Starting Address Low ($F0)
byte 5: No. of Registers High ($00)
byte 6: No. of Registers Low ($01)
byte 7: CRC_Low
($XX)
byte 8: CRC_High
($XX)
A.10.
Discrete Commands (Coils, 0x References)
The ASTAT-XT incorporates 16 "Coils", (bit parameters), of which only 5 are operative. The other 10 are reserved and
were incorporated to enable the user to use word (16 bits) type parameters. Coil # is 1"1 based". The actual address
is 1 lower than coil #. For example coil #1 is addressed as 0 (00000). The coils have the following 0x references:
Coil # Coil Address
Use in ASTAT-XT
Comment
1 0 Stop
Write
"1"
(ON)
to
stop.
2
1
Soft Stop
Write "1" (ON) to Soft Stop
3 2 Start
Write
"1"
(ON)
to
start
4
3
Energy Save
Write "1" (ON) to turn On. Write "0" (OFF) to turn Off.
5
4
Dual Adjust
Write "1" (ON) to turn On. Write "0" (OFF) to turn Off.
6
5
Slow Speed
Write "1" for Slow Speed. Write "0" for Normal Start.
7
6
Slow Spd Reverse
Write "1: for Reverse Direction. Write "0" for Forward Direction
8 7 Reset
Write
"1"
(ON)
to
Reset.
9..16
8..15
Reserved
Example 6 - Read Coils:
To read coils 1..8 status of ASTAT-XT # 10, the host computer sends the following Query frame:
byte 1: Serial Link No.
($0A)
byte 2: Function
($01)
byte 3: Starting Address High
($00)
