Despatch Protocol Plus Modbus Communications - Manual (Page 5)

Chromalox Instruments and Controls
A-51643 Rev. 6 10/06/03 iv
6.7.1 The Byte Count Field ............................................................................................................................. 41
7 PROGRAMMING EXAMPLE AND GENERAL HINTS ............................................................................ 42
7.1 C ODE E XAMPLE .......................................................................................................................................... 42
7.2 A DDITIONAL C OMMUNICATIONS T ROUBLESHOOTING H INTS ...................................................................... 47
List of Figures and Tables
T ABLE 1: M ODBUS R EFERENCES .................................................................................................................................... 1
T ABLE 2: P ROTOCOL
TM
P LUS R EFERENCES .................................................................................................................... 1
F IGURE 1: RS232 W IRING ............................................................................................................................................. 2
F IGURE 2: RS422A W IRING (4 WIRE ) ............................................................................................................................ 3
F IGURE 3: RS485 W IRING (2 WIRE ) ............................................................................................................................... 3
F IGURE 4: C ONTROLLER R EAR V IEW WITH C OMMUNICATION C ARD (L EFT ) .................................................................. 4
F IGURE 5: C OMMUNICATION C ARD (0113-10175) J UMPER S ETTINGS ............................................................................ 5
T ABLE 3: P ROTOCOL
TM
P LUS D ISCRETE I NPUT A DDRESS M AP ...................................................................................... 6
T ABLE 4: P ROTOCOL
TM
P LUS D ISCRETE O UTPUT A DDRESS M AP ................................................................................... 7
T ABLE 5: P ROTOCOL
TM
P LUS I NPUT R EGISTER A DDRESS M AP ....................................................................................... 8
T ABLE 6: P ROTOCOL
TM
P LUS H OLDING R EGISTER A DDRESS M AP ............................................................................... 10
T ABLE 7: C OMMUNICATION S ECURITY L EVELS ........................................................................................................... 15
T ABLE 8 P ROTOCOL
TM
P LUS F UNCTION AND E XCEPTION C ODE S ET .......................................................................... 20
T ABLE 9 P ROTOCOL
TM
P LUS D IAGNOSTIC (F UNCTION C ODE 08) S UB - FUNCTION S ET ................................................ 20
T ABLE 10 P ROTOCOL
TM
P LUS E XCEPTION C ODE S ET ................................................................................................. 21
T ABLE 11: P ROTOCOL
TM
P LUS D IAGNOSTIC R EGISTER B IT A SSIGNMENT .................................................................... 30
F IGURE 6 CRC F LOWCHART ....................................................................................................................................... 40