Watlow PPC-2000 - Manual (Page 308)

Appendix A: Modbus Protocol PPC-2000 User’s Guide
280 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Examples
Read Examples
The data read must be sequentially located. When reading a
coil rather than a register, the address must be offset by the
location of the bit to read. Table A.3 shows the query and Table
A.4 shows the response:
Table A.3 Sample Packet for Host Query
Table A.4 Sample Packet for Slave Response
Example
Slave
Address
Function
Start
Address
High
Start
Address
Low
Number
of
Points
High
Number
of
Points
Low
CRC
Reading PV of
loop 2 controller 1
(single point read)
01 04 0B B9 00 01 E2 0B
Reading loops 4
& 5 (primary) out-
put% of controller
3 (multipoint read)
03 03 18 9F 00 02 F3 67
Reading digital
input 4 to 13,
controller 1
(input status read)
01 01 0B BB 00 10 4F C7
Example
Slave
Address
Function
Byte
Count
Data1
High
Data1
Low
Data2
High
Data2
Low
CRC
Reading PV of
loop 2 (1600),
controller 1 (single
point read)
01 04 02 06 40 BB 60
Reading loops 4 &
5 (primary) out-
put% (50%, 60%),
of controller 3
03 03 04 01 F4 02 58 99 67
Reading digital
input 4 to 13,
controller 1 (input
status read)
01 01 02 08 00 BE 3C