Flowserve DDC-100 Modbus Direct-to-Host - Manual (Page 12)

18 DDC-100 Direct-to-Host Programming Guide FCD LMAIM4019-00 FCD LMAIM4019-00 DDC-100 Direct-to-Host Programming Guide 19
3.2.4 Modbus Function Code 04 (Read Input Register)
This function code is used to read the binary contents of input registers in the DDC-100 Field
Unit. The typical use of this function code is to read the analog input registers. If the field unit is
configured for scaled analog data, the register information will be returned as a percent from 0 to
100 (see NOTE below). The first analog input register (Analog 4) will start at register 30005 through
(Analog 1) Input Register 30008.
This function code may also be used to read the information available in registers 9 through 16.
NOTE: Limitorque field units can be configured to report analog data in several formats. See the
appropriate field unit manual for details.
Example
Poll field unit number 70 for 4 registers starting at register 5 (Analog Input Registers 1-4).
(This example assumes that the field unit is configured for scaled analog data.)
Query 460400040004BF7F
Response 460408FFFFFFFF002B001EDBA8
Message Breakdown
Query Response
46 Slave (Field Unit) Address 46 Slave (Field Unit) Address
04 Function 04 Function
00 Starting Address Hi 08 Byte Count
04 Starting Address Lo FF Data Hi (Register 40005)
00 No. of Points Hi FF 1 Data Lo (Register 40005)
04 No. of Points Lo FF Data Hi (Register 40006)
BF7F Error Check (CRC) FF 2 Data Lo (Register 40006)
00 Data Hi (Register 40007)
2B 3 Data Lo (Register 40007)
00 Data Hi (Register 40008)
1E 4 Data Lo (Register 40008)
DBA8 Error Check (CRC)
Note 1: FFFFh equals 65535 Decimal (actuator Analog Input 4 value).
Note 2: FFFFh equals 65535 Decimal (actuator Analog Input 3 value).
Note 3: 002Bh equals 43 Decimal (actuator Analog Input 2 value).
Note 4: 001Eh equals 30 Decimal (actuator Analog Input 1 in percent format).
3.2.5 Modbus Function Code 05 (Force Single Coil)
This function code is used to force a single coil in the DDC-100 Field Unit. Forcing the individual coil
either ON (1) or OFF (0) will energize or de-energize a coil (digital output) in the field unit. Coil 1 in
the field unit closes the actuator and Coil 2 opens the actuator. If the actuator is opening or closing,
changing the status of coil 1 or 2 from a value of 1 to 0 will stop the actuator (the coil will automati-
cally be set to zero when the actuator reaches the full open or full close position).
Available digital outputs for DDC-100 Field Units are listed in Table 3.6. Force-coil commands
should be issued only once for the desired field unit control. Repeated issuance of an acknowl-
edged command will degrade network performance.
NOTE: See Bulletin LMAIM1329, Accutronix Installation and Operation for MX-DDC Field Unit to
configure AS and AR Relays for DDC control.
Table 3.6 – DDC-100 Coil Assignments Modbus Function Code 05 Usage for Digital Outputs
Coil
Number
Bit
Number
MX/DDC UEC-3-DDC DDC-100 Clamshell I/O Module
1 00 Close / Stop Close / Stop Close / Stop Do Not Use
2 01 Open / Stop Open / Stop Open / Stop Do Not Use
3 02 AS-1 Lockout or Relay #3 Lockout or Relay #3 Relay #3
4 03 AS-2 Do Not Use Relay #4 Relay #4
5 04 AS-3 Do Not Use Relay #5 Relay #5
6 05 AS-4 Relay #6 Relay #6 Relay #6
7 06 AR-1 (Opt) Do Not Use Do Not Use Relay #21
8 07 AR-2 (Opt) Do Not Use Do Not Use Relay #12
9 08 AR-3 (Opt) Do Not Use Do Not Use Do Not Use
Note 1: Relay #2 is physical Relay K2.
Note 2: Relay #1 is physical Relay K1.
The normal response to the (05) command is an echo of the command.
Example of force coil command
Force coil 1 of field unit 49 ON. This will CLOSE the valve controlled by field unit 49.
Query 31050000FF0089CA
Response 31050000FF0089CA
Message Breakdown
Query Response
31 Slave (Field Unit) Address 31
Slave (Field Unit)
Address
05 Function 05 Function
00 Coil Address Hi 00 Coil Address Hi
001 Coil Address Lo 00 Coil Address Lo
FF Force Data Hi FF Force Data Hi
002 Force Data Lo 00 Force Data Lo
89CA Error Check (CRC) 89CA Error Check (CRC)
Note 1: 0000h equals Coil Address 00000001 (field unit coil 1).
0001h equals Coil Address 00000010 (field unit coil 2).
Note 2: FF00h requests the coil to be ON. (0000h requests the coil to be OFF)
3.2.6 Modbus Function Code 06 (Preset Single Register)
This function code is used to preset a single register in the field unit. The function code is typically
used to command the DDC-100 Field Unit by writing values to the 40001 and 40002 registers. A
predetermined value may be used to open/stop/close the actuator, move the actuator to a preset
position, activate/deactivate network ESD, reset the field unit, etc.
The Modbus function code 06 is also used to command a throttling actuator to “move-to” a posi-
tion of 0-100% of open. The field unit will compare the new position value with the current position
and open or close the valve to meet the new position requirement. This is a two-step command: the
first step is to write the desired position value to the field unit register 40002, then write the value
of 6656 to field unit register 40001. This sequence of commands loads the desired position, then
instructs the field unit to execute the command.
For UEC-3-DDC field units containing Modbus Firmware 2.00 or greater and MX-DDC field units
containing Firmware 02/01.00 or greater, the “move-to” command may be executed with a one-step
command.